Marines target rebels in Fallujah region

The operation was under way amid fears for the safety of diplomats in Iraq. The government appealed to its global partners to defy al-Qa'ida's "blackmail" and keep their diplomats in Baghdad despite the reported slaying of Egypt's top envoy and threats against those who support the US-backed administration.

Operation Scimitar began on Thursday with targeted raids in the village of Zaidan, 20 miles from Fallujah. So far, 22 suspected insurgents have been detained. Fallujah was a major insurgent bastion until US forces overran the city in November. The campaign includes 500 Marines from the 3rd Reconnaissance Battalion, stationed in Okinawa, Japan. About 100 Iraqi soldiers are supporting the operation.

Elsewhere, gunmen yesterday killed a police captain, Saad Mihsin Abdul Sadah, in Amiriyah, some 25 miles west of Baghdad. He was on his way to work at the Interior Ministry, police said. The insurgency has frequently targeted Iraq's security forces, but started attacking foreign diplomats in recent days as part of a new trend apparently aimed at isolating the country from the Arab world.

Violent incidents in the capital have been declining since Iraq's US-backed forces launched an operation against insurgents in the city six weeks ago. The commander of US forces in Baghdad, General William Webster, said car bombings had dropped from 14 to 21 a week in May to seven or eight a week now. But he said it was "very difficult to know" whether the insurgency has been broken.

Iraqi officials have become concerned about a possible exodus of diplomats from Baghdad after a website claim on Thursday by al-Qa'ida in Iraq that it had killed the Egyptian envoy Ihab al-Sherif, who was seized by eight gunmen on a street in Baghdad last weekend.

The terror group said it wanted to seize "as many ambassadors as we can" to punish states that support Iraq's Shia-dominated government. Sunni Muslims, who dominated Iraq until Saddam was ousted in 2003, now make up the core of an insurgency that has killed more than 1,475 people since the government took office on 28 April.