Thousands of Iranians are converging¹ on the city of Qom for the funeral of leading reformist cleric Grand Ayatollah Hoseyn Ali Montazeri.

成千上万的伊朗人聚集到库姆参加改革派领导牧师大阿亚图拉侯赛因·阿里·蒙塔泽里的葬礼。

Opposition² leaders have called for Monday to be a national day of mourning and reformist websites report an increased security presence in Qom.

Correspondents say the government could face a major challenge in how it deals with the funeral.

The grand ayatollah阿亚图拉 was one of Shia Islam's most respected figures.

He was an architect建筑师 of the 1979 revolution that created Iran's Islamic state but later became a vocal³ critic of the government.

He died of natural causes in Qom on Saturday night at the age of 87.

The funeral is scheduled to start in the main shrine圣地，神殿 in Qom, 125km (78 miles) south of Tehran, at 0900 local time (0530 GMT).

Opposition leaders Mir Hossein Mousavi and Mehdi Karroubi have been quoted on reformist websites as calling for a large turnout.

One website that backs Mr Mousavi, Kaleme, quoted them as saying: "We invite all saddened religious people mourning the death of this pride of the Shiite world to take part in the funeral of this legend of endeavour尽力，竭力, jurisprudence法律知识 and spirituality灵性，精神性."

The BBC's Jon Leyne says the government will clearly fear a large turnout and asks whether its leaders can really be seen trying to prevent mourners marking the death of a grand ayatollah.

Doing so could risk a repeat of the street protests that followed Iran's disputed presidential election in June.

Arrest

On Sunday a large crowd of mourners quickly gathered outside the grand ayatollah's home in Qom to pay respects.

Video footage on internet sites also showed hundreds of mourners on the streets of the grand ayatollah's home town of Najafabad.

Sporadic⁵ gatherings⁶ were reported in Tehran and other cities.

One website, Jaras, said a student of the grand ayatollah, Ahmad Qabel, had been detained on his way to the funeral.

Foreign media have been restricted in Iran since the post-election protests and it is often difficult to verify reports. No foreign media will be allowed to attend the funeral.

The government has made no direct comment on the security situation.

Supreme⁷ Leader Ayatollah Ali Khamenei did offer his condolences on Sunday, praising Grand Ayatollah Montazeri as an outstanding jurist法官，律师.

However, the supreme leader tempered this with criticism, saying he hoped God would forgive the grand ayatollah for failing his "crucial test".

This was a reference to Grand Ayatollah Montazeri's falling out with the leader of the revolution, Ayatollah Ruhollah Khomeini.

State news agency Irna did not use the ayatollah title in its early reports of Grand Ayatollah Montazeri's death and referred to him as the "clerical figure of rioters暴徒，暴民".

The White House, however, praised the grand ayatollah, saying he was his "known and internationally respected for his unwavering不动摇的，坚定的 commitment to universal rights".