Iraqi authorities extended a daytime curfew on Baghdad today after one of the bloodiest weeks this year.
US military spokesman
State television announced that a four-hour traffic ban in force every Friday to curb car bomb attacks on mosques during weekly prayers would be extended through most of the day.
A gun and grenade attack on a market just outside Baghdad on Monday and a suicide car bombing to the south of the capital killed 120 people this week.
US data showed attacks on security forces in Baghdad has averaged 34 a day over several days, compared to an average of 24 in recent months. Baghdad's morgue has taken in 1,000 bodies this month.
US commanders are speaking about an all-out battle in the capital between Shia Prime Minister Nuri al- Maliki's two-month-old unity government and Sunni Arab rebels with links to al-Qaeda and ousted president Saddam Hussein.
The US ambassador has warned that a greater threat may be the mounting sectarian violence between minority Sunnis and the Shias empowered by the US invasion which ousted Saddam.
A US military spokesman conceded that Mr Maliki's month-old security operation in Baghdad had achieved only a "slight downtick" in violence, with civilian deaths steady.
"We have seen the movement of terrorist elements into the Baghdad area. We have seen the flow occurring."
US-led forces have also been cracking down on Shia warlords, many of them apparently rogue elements of pro-government militias that Mr Maliki has promised to rein in.