Hong Kong: Oil prices climbed on Wednesday while Asian stocks slipped as renewed concerns over Middle East supply resurfaced, with fresh attacks in the Strait of Hormuz and a Saudi-led coalition saying it had intercepted a Houthi missile headed towards the kingdom.

The developments added to market anxiety over energy flows from the region, even as traders had been reassured earlier this week by signs that oil exports from the Middle East, excluding Iran, were recovering towards pre-war levels.

Global benchmark Brent crude had fallen below $100 a barrel and West Texas Intermediate below $90 as improving export flows eased fears of prolonged supply disruptions and gave central banks some breathing room on interest rates.

But both benchmarks rebounded on Tuesday and extended gains in early Asian trading after figures indicated that Iran had stepped up attacks on tankers passing through the Strait of Hormuz, one of the world's most important oil shipping routes.

UK Maritime Trade Operations said nine attacks had been reported so far this month — half the number recorded across the waterway and the Persian Gulf during the whole of September.

The latest escalation came as Yemen's Iran-backed Houthis claimed to have attacked Riyadh's main airport, while denying government claims that their forces had been pushed back in a major counter-offensive.

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The Saudi-led coalition said on Tuesday that it had "intercepted and destroyed" a ballistic missile launched by the Houthis towards Khamis Mushait in southwestern Saudi Arabia, where a major airbase is located.

The Houthis had earlier claimed an attack on Riyadh airport and a Saudi Aramco refinery. Loud explosions were heard across the Saudi capital on Monday evening, followed by another blast that echoed through northern parts of the city on Tuesday, residents told AFP.

Saudi authorities have not publicly confirmed any attack on the airport. The civil aviation authority, however, said at least three people were wounded in attacks on Jazan and Najran airports near the Yemen border on Monday.

Riyadh's King Khalid International Airport has also been facing frequent temporary airspace closures, according to flight-tracking website Flightradar24, although Saudi authorities have not publicly acknowledged the closures.

The escalation in Yemen has added another layer of uncertainty to an already volatile regional energy market.

The Houthis said they still controlled all the territory they seized last month along Yemen's Red Sea coast, while the Yemeni military said it had driven the group from areas around the Bab al-Mandeb strait and the port city of Mocha.

Claims from both sides could not be independently verified as fighting intensified and access for journalists remained difficult.

Sources on both sides told AFP that more than 270 government troops and Houthi fighters had been killed in fighting across Yemen over the previous 24 hours.

Houthi military spokesman Yahya Saree said the group still had "full control over all their advances on the ground".

He said Houthi forces had carried out dozens of attacks against government troops in Al-Jawf and Marib, while also targeting positions in Taiz.

Saree later said the Houthis had pushed back government forces "as they attempted to advance towards our forces' positions southwest of Al-Waziya", a strategically important area near the Bab al-Mandab strait.

The Houthi health ministry also said a Saudi airstrike had killed six members of a family, including four children, in a village in Hajjah governorate. The claim could not be independently verified.

Hormuz remains the bigger oil-market concern

For oil traders, however, developments around the Strait of Hormuz remain the immediate focus.

The waterway carries a significant share of global oil supplies, making any sustained disruption a major threat to energy markets. Fresh attacks on vessels have therefore offset some of the relief provided by signs that regional exports were recovering.

"Reports of increased flows across the region have offered some downside pressure on crude, but this has been offset by varying reports around the scale of attacks on vessels moving through the Strait," said Chris Weston at Pepperstone.

"For now, the market remains highly sensitive to headlines and geopolitical risk."

Top oil officials have also warned that global stockpiles are running low, potentially reducing governments' ability to absorb a prolonged disruption to supplies.

Asian stocks retreat

The renewed geopolitical concerns came after another record-setting session on Wall Street, where investors continued to pile into artificial intelligence-related stocks.

The Nasdaq and S&P 500 hit fresh records, helped by gains in Nvidia, whose market capitalisation approached $6 trillion. Its valuation reached almost $5.7 trillion during Tuesday's session.

Investors were also encouraged by a Financial Times report that SpaceX was seeking to raise $40 billion to purchase Nvidia chips.

The renewed enthusiasm for technology stocks comes after a summer sell-off sparked concerns that massive investment in AI could have run ahead of potential returns.

Asian markets were less optimistic on Wednesday. Tokyo, Hong Kong, Singapore, Seoul, Wellington and Taipei all fell, while Sydney and Manila edged higher.

Analysts expect the latest US earnings season to show S&P 500 profits rising by about a quarter year-on-year, according to Bloomberg Intelligence data.

Yemen conflict adds to regional risk

Saudi Arabia, the main backer of Yemen's internationally recognised government, has been providing air support for the military's counter-offensive against the Houthis.

The Yemeni government says it wants to retake all Houthi-held territory, much of which has been under the group's control for more than a decade.

Government forces claimed "victories on several fronts" late Monday and said they had made gains in Taiz and southern Marib. Military sources stopped short of confirming that Mocha had been recaptured, saying only that the main supply route into the port city had been cut.

A 33-year-old charity worker who fled Mocha for Aden described the situation to AFP.

"Life in Mocha has come to a complete standstill -- there is no movement at all. The city has become a war zone," he said.

The renewed fighting comes after years of relative calm in Yemen and amid a wider Middle East conflict that began with US-Israeli strikes on Iran in February.

The Houthis last month seized Yemen's entire western coastline along the Red Sea in the deadliest fighting the country has seen in years. They have also targeted Saudi oil and military infrastructure and declared a maritime blockade on Saudi-linked shipping.

Pakistan and Turkey on Monday pledged to deploy troops to Saudi Arabia under a mutual defence pact.

Hamish Kinnear, an analyst with UK-based Verisk Maplecroft, said the deployment "is likely to mean Turkey and Pakistan helping to intercept Houthi missiles and drones".

He added that Turkey and Pakistan "will emphasise that their deployment is to support the Saudis and counter the Houthis, not to antagonise Iran and support the US".

But "that distinction will become harder to maintain if the regional conflict continues to escalate".

Oil, currencies and stocks

At around 0230 GMT on Wednesday, West Texas Intermediate was up 1.0 per cent at $90.29 a barrel, while Brent crude rose 0.9 per cent to $101.48.

The Nikkei 225 fell 0.9 per cent to 70,074.13, while Hong Kong's Hang Seng Index dropped 0.7 per cent to 24,108.15. Shanghai markets were closed for a holiday.

The dollar rose to 158.38 yen from 158.17 yen on Tuesday. The euro weakened to $1.1234 from $1.1257, while the pound fell to $1.3251 from $1.3275.

In New York, the Dow Jones Industrial Average gained 0.5 percent to close at 51,521.28, while London's FTSE 100 rose 0.4 percent to 10,541.69.