The remains of Iran's late supreme leader Ayatollah Ali Khamenei have been carried through two of Shia Islam's holiest shrines in neighbouring Iraq, as funeral ceremonies continue for a fifth day.

Huge crowds filled the city of Najaf for a procession that ended at the mausoleum of Imam Ali, the Prophet Muhammad's son-in-law and first Shia Imam. Inside, mourners jostled to touch the coffin before prayers were held.

It was later flown to the city of Karbala and taken through more crowds to the mausoleum of Imam Hussein, the prophet's grandson.

Khamenei, who was killed on the first day of Iran's war with the US and Israel, will be buried on Thursday in Mashhad, in north-eastern Iran.

Among the tens of thousands of mourners who gathered in Najaf on Wednesday morning was Mohammed al-Bayati, 30, who told AFP news agency: "This is an opportunity not to be missed - to take part in the funeral of the person who challenged the power of America and Israel."

Chants of "Death to America" and "Death to Israel" were also heard as Khamenei's coffin was transported by a lorry towards the shrine of Imam Ali.

Video footage showed mourners pushing and shoving each other to get close to the casket as it was carried by hand through the mausoleum's halls. A senior cleric from Najaf's Shia seminaries then led the funeral prayers.

Later on Wednesday, Khamenei's coffin arrived in Karbala, about 60km (37 miles) north of Najaf, for another funeral procession that ended at the shrine of Imam Hussein. His death in battle there in the 7th Century cemented the schism between Shia and Sunnis.