Mashhad: The coffin of Iran's late Supreme Leader Ayatollah Ali Khamenei arrived in Mashhad on Thursday ahead of his final burial, but the funeral ceremony was briefly delayed after an overwhelming number of mourners gathered at the Imam Reza Shrine.

Officials postponed the burial to ensure crowd safety as thousands of people packed the shrine and surrounding streets to pay their last respects.

The Imam Reza Shrine, one of the holiest sites in Shia Islam, had been chosen as Khamenei's final resting place.

The funeral in Mashhad marked the last stage of a multi-city farewell that began in Tehran and continued through the religious city of Qom.

The coffin was also taken to the Iraqi holy cities of Najaf and Karbala before returning to Iran for the burial.

Iranian authorities had earlier estimated that between 15 million and 20 million people would take part in the funeral ceremonies, making it one of the largest public gatherings in the country's history.

Thousands of mourners carrying portraits of Khamenei and waving Iranian flags lined the streets as the coffin made its way to the shrine.

The temporary delay added several hours to the schedule before officials resumed the ceremony under heightened security arrangements.

State media later confirmed that Khamenei was laid to rest at the Imam Reza Shrine, bringing the days-long funeral proceedings to an end.

The funeral has drawn political leaders, senior clerics and delegations from several countries, while large crowds continued to gather outside the shrine despite the delay.

The ceremonies have taken place amid heightened tensions in the region, with authorities maintaining tight security throughout the events.

Time and venue

Iran's state news agency IRNA broadcast footage of a Mahan Air flight carrying Ayatollah Ali Khamenei's coffin as it landed at Mashhad Airport on Thursday. The burial, which was initially scheduled for Thursday morning, was postponed after huge crowds in Iraq slowed the final leg of the funeral procession.

Iranian state television later announced that the ceremony would instead be held at 2:30 pm local time (4:30 pm IST).

Mashhad holds immense religious importance in Iran as it is home to the Imam Reza Shrine, where Imam Ali Ibn Musa al-Ridha, the eighth Imam of Twelver Shia Islam, is buried.

Considered the country's spiritual heart, the shrine is one of the holiest sites in Shia Islam and attracts millions of pilgrims from across the world each year.