A hospital has been razed to the ground in one of the heaviest US air raids in the Iraqi city of Falluja.
The hospital was run by an Islamic charity
Witnesses said only the facade remained of the small Nazzal Emergency Hospital in the centre of the city. There are no reports on casualties.
A nearby medical supplies storeroom and dozens of houses were damaged as US forces continued preparing the ground for an expected major assault.
UN chief Kofi Annan has warned against an attack on the restive Sunni city.
It is the third time since the end of the US-led war that US and Iraqi forces have tried to gain control of Falluja.
They say militants loyal to top al-Qaeda suspect Abu Musab al-Zarqawi are hiding there.
Zarqawi's supporters have been behind some of the worst attacks on coalition and Iraqi forces as well as dozens of kidnappings. Some of the hostages - foreigners and Iraqis - have been beheaded.
US troops using 155mm howitzers pounded a number of pre-planned targets in Falluja on Saturday.
Along with air strikes - one of the heaviest in recent days - this is all part of what appears to be a steadily increasing pressure on the insurgents, says the BBC's Paul Wood, who is with US marines outside Falluja.
Overnight, a column of armoured vehicles and humvee jeeps carried out attacks in the outskirts of Falluja designed to draw out the rebels and provide fresh targets for the air power and artillery.
These are the kind of preliminary operations which would be carried out before a full-scale assault on Falluja, our correspondent says.
The air strikes reduced the Nazzal hospital, run by a Saudi Arabian Islamic charity, to rubble.
Hospital officials quoted by Reuters news agency say all the contents were ruined.
Apr 2003: US paratroopers shoot dead 13 demonstrators
Nov 2003-Jan 2004: attacks on three US helicopters kill 25
Feb 2004: 25 killed in attacks on Iraqi police
31 Mar 2004: four US contractors killed
Apr 2004: US seals off city
May 2004: Siege lifted
June 2004: Zarqawi loyalists targeted in US raids - continuing to date
Oct 2004: Iraqi PM threatens military action if Zarqawi is not handed over
More people were preparing to flee the city - more than half of the city's estimated 300,000 people have already left.
US marine officers say the full-scale attack will go ahead only once Iraqi Prime Minister Iyad Allawi has given the order.
"The window really is closing for a peaceful settlement," Mr Allawi said on Friday after meeting EU leaders in Brussels.
In a letter to the leaders of the US, UK and Iraq, UN Secretary General Kofi Annan warned that the use of force risked alienating Iraqis when their support for elections was vital.
But Mr Allawi called the letter "confused".
He said if Mr Annan thought he could prevent insurgents in Falluja from "inflicting damage and killing", he was welcome to try.