Critics of the Bush administration's handling of escalating violence in Iraq should "just back off" on demands for deadlines for Iraqi forces to take over security operations, U.S. Defence Secretary Donald Rumsfeld said Thursday.

Rumsfeld, who has come under increased fire for his role in the U.S. strategy in Iraq, made the comments on the same day as the number of U.S. soldiers killed in Iraq this month reached the highest monthly total in a year.

The U.S. military said Thursday that 96 U.S. troops have died so far in October, the most in one month since October 2005, when the same number were killed.

Four marines and a sailor died of wounds suffered while fighting in the same Sunni insurgent stronghold in the volatile Anbar province, while a desperate search continued Thursday for a soldier who went missing Monday in Baghdad.

Anti-war sentiment high

The rise in deaths has been a major factor behind rising anti-war sentiment in the United States and has placed increased pressure on the White House to change tactics to curb escalating violence in the country.

Rumsfeld also refused to say whether he will authorize more troops to fight the war, but said the U.S. would increase its support for Iraqi security forces.

"You ought to just back off, take a look at it, relax, understand that it's complicated, it's difficult," Rumsfeld said regarding demands for deadlines. "Honourable people are working on these things together."

He said the timelines have no specific deadlines, or consequences if goals are not met by specific dates.

"You're looking for some sort of a guillotine to come falling down if some date isn't met. That is not what this is about," he said.

Polls show a majority of Americans are opposed to U.S. President George W. Bush's handling of Iraq, and at a news conference in Washington on Wednesday, the president indicated he shared the public's frustration, even as he pushed back against calls for troop withdrawals.

"I know many Americans are not satisfied with the situation in Iraq," Bush said. "I'm not satisfied either."

The deadliest month for U.S. forces in Iraq was November 2004, when military offensives primarily in the then-insurgent stronghold of Fallujah, 70 kilometres west of Baghdad, left 137 troops dead, 126 of them in combat. In January 2005, 107 U.S. troops were killed.

In other violence, 12 police officers were killed in fighting with suspected militia gunmen in Baqouba, northeast of Baghdad, officials said. Eighteen militants were also killed.

Gen. William Caldwell, the U.S. military spokesman, said there had been a marked decrease in violence in Baghdad since the end of Ramadan, the Muslim month of fasting, earlier this week.

Caldwell said violence has in the past tended to spike during that month before falling off. He also said it was possible increased U.S. patrols and roadblocks in the search for the missing American soldier could be having an effect.

With files from the Associated Press