Iraqi rebels staged a show of strength in the western Iraqi city of Ramadi today, attacking a US base and a local government building before seizing control of some streets.
Some 400 heavily armed men set up roadblocks at major entrance and exit points to the city - a heartland of the insurgency in Iraq - and patrolled the main thoroughfares, residents said.
In some areas they dispersed after a few hours, but militants remained in other parts.
Leaflets were distributed and posted on walls saying al-Qaeda in Iraq, the group led by Jordanian militant Abu Musab al-Zarqawi, was taking over the city.
"Its followers will burn the Americans and will drive them back to their homes by force. Iraq will be a graveyard for the Americans and their allies," one of the leaflets read.
An Internet posting from the group said the attack, dubbed "Battle of the Lions", was carried out to expose "the falseness of the crusaders' claims about their imaginary 'Steel Curtain'".
It was referring to a recent US-led operation in western Iraq which officials said killed hundreds of insurgents.
After the initial attack, the situation calmed down, with groups of masked men holding ground but not firing their weapons.
In other parts of the city the rebels dispersed, and some residents said US forces were starting to patrol again.
The assault on Ramadi, capital of Anbar province, began early today with a mortar and rocket attack on a US base in the city and on a nearby provincial governor's building.
"They've taken control of all the main streets and other sections of Ramadi," a reporter for Reuters news agency there said earlier.
"I've seen about 400 armed men controlling streets, some of which were controlled by Americans before."
The US military did not immediately respond to a request for information about the situation.
The US military has a fortified garrison in Ramadi, and usually ventures out to conduct patrols and other operations.
Iraqi forces also have bases there. Ramadi has long been a focal point of militant activity in Iraq.
After US forces overran Falluja in a massive offensive last November, many insurgents apparently fled west to Ramadi, which is about 60 km (40 miles) beyond Falluja.
Today's assault came the day after US President George W. Bush announced details of his strategy in Iraq, saying more efforts would be made to train Iraqi security forces to take on insurgents so that US forces could eventually withdraw.