Taipei: A 6.6-magnitude earthquake struck off Taiwan's northeastern coast on Saturday, the US Geological Survey (USGS) said, the second major tremor to hit the island within days.

Taiwan's weather agency, which put the magnitude at 7.0, said the quake hit at 23:05 pm (1505 GMT) at a depth of 73 kilometres (45 miles) in the sea off Yilan county, southwest of Taipei.

The Yilan County Fire Bureau told AFP there were no immediate reports of casualties or damage.

Local media said the quake caused buildings in the capital Taipei to sway and was felt across Taiwan.

Taiwan is frequently hit by earthquakes due to its location on the edge of two tectonic plates near the Pacific Ring of Fire, which the USGS says is the most seismically active zone in the world.

On Wednesday, a 6.0-magnitude tremor struck the island's southeast.

In April 2024, a 7.4-magnitude earthquake killed 17 people as it triggered landslides and severely damaged buildings around Hualien city.

Officials at the time said it was Taiwan's strongest quake in 25 years.

It was the most serious in Taiwan since a 7.6-magnitude tremor struck in 1999 – the deadliest natural disaster in the island's history.  (AFP)