Thousands of Iraqi Shia Muslims on Tuesday staged noisy demonstrations outside the main hotel housing the international media in Baghdad, calling for the release of a senior cleric they said had been arrested by US forces.
The first protest late on Monday afternoon took the media and US forces by surprise when about 4,000 Shia men converged on the Palestine Hotel from both the north and south.
Demonstrators called for US forces to leave Iraq
It was extremely well regimented, with long-robed and turbaned clerics first ordering the crowd to sit down in Saadun Street, just under the broadcasting positions of the assembled television news organisations.
The chanting began with the now-obligatory call for Islamic unity between the majority Shia and their Sunni Muslim counterparts.
This has become the clarion under which both Shia and Sunni demonstrate in Iraq, a reflection of the fears many have at the horrific implications of internecine conflict between the two groups.
The protesters then demanded the immediate release of a cleric said to have been arrested by the US - Sheikh Muhammad al-Fartusi who is the representative in Baghdad of the powerful Hawza council of Ulema, based in Najaf.
Within hours, it was reported that the cleric had been released from custody, although US officials have never confirmed he was initially detained.
Protesters also chanted "No colonialism", a reference to fears of US intentions in Iraq, and "Yes, Yes, to Islam, no America and no Saddam".
Such unrest as that sparked by Fartusi's alleged arrest could turn into a serious problem for the US military
authorities here, because if the Shia Ulema withdraw co-operation it would make American plans for post-Saddam Iraq almost impossible to realise.
There is a strong desire among the Shia for an Islamic administration following the overthrow of Saddam Hussein's Arab nationalist government.
Sheikh Hussein al-Assadi, a member of the Hawza council who described himself a student of Sheikh Fartusi, warned at the scene of the protest that US forces in Iraq should be aware of Muslim sensitivities "otherwise there will be an explosion".
"We suffered under Saddam, we don't want to suffer under the Americans too," he said.
After about an hour's chanting on Monday night, there came a signal from one of the organising clerics held shoulder-high among the crowd as they beat their chests in the traditional Shia fashion and the demonstrators marched away north up Saadun Street.
A smaller group, with fewer than 1,000 protesters returned to the same spot on Tuesday morning where they resumed calls for Sheikh Fartusi's release and chanted Shia religious slogans.
This week the Shia community are staging one of the biggest events in their religious calendar, long suppressed by the government of Saddam Hussein.
More than one million people are estimated to be heading for Karbala to commemorate the death of the Imam Hussein, grandson of the Prophet Muhammad.