Baghdad, 30 November 2004 - Disintegrating security in Baghdad was underlined in a sombre warning yesterday from the British embassy against using the airport road or taking a plane out of Iraq.

The embassy says a bomb was discovered on a flight inside Iraq on 22 November. It shows that insurgents have been able to penetrate the stringent security at Baghdad airport. The embassy says its own staff have been advised against taking commercial planes.

The warning is in sharp contrast to more optimistic statements from US military commanders after the capture of Fallujah in which they have spoken of "breaking the back of the insurgency".

The embassy says that the road between Baghdad and the international airport, perhaps the most important highway in the country, is now too dangerous to use. The advice says starkly: "With effect from 28 November, the British embassy ceased all movements on the Baghdad International airport road."

The airport road is littered with evidence of previous attacks: the twisted cars used by suicide bombers and craters from roadside bombs.

There are no safe havens. Since March, 14 British civilians have been killed. Not only have insurgents proved capable of putting a bomb on a plane, but on 14 October two suicide bombers entered the heavily fortified Green Zone and blew themselves up, killing five people and injuring many more.

Danger levels in the capital are also increasing; some of the resistance fighters who were previously in Fallujah have taken refuge in Baghdad. They may wish to launch spectacular attacks to offset the fall of Fallujah, which had been the de facto capital of the insurgents.

The Iraqi government and the US Army suffered losses yesterday from two of the insurgents' favourite weapons: suicide bombs and roadside bombs. No effective defence has been found against either.

A suicide bomb killed seven Iraqi soldiers and police and wounded nine in an attack in the town of Baghdadi, 120 miles north-west of the capital. Two US soldiers were killed and three wounded by a roadside bomb in north-west Baghdad. Hitherto, roadside bombs have consisted of several artillery shells detonated by a command wire or by remote control. But the US military say the insurgents have started using shaped charges which direct the blast towards a target.

The battle for Fallujah was largely successful from the US point of view, because the assault did not provoke the widespread nationalist reaction across Iraq as seen in April, when theAmericans first attacked the city.

Many Shia Iraqis had come to see Fallujah as the headquarters of extreme sectarian Sunnis, whose suicide bombers have slaughtered mostly Shia police and army recruits. Many were pleased to see Fallujah insurgents killed or dispersed.

But the capture of the Fallujah may have less military affect than the US and the Iraqi interim government had hoped, because the Sunni uprising is very fragmented and does not appear to have a central command. Observers in Fallujah during the US attack say the siege was never complete and many fighters slipped out. They add that if the US figure of 1,200 insurgents killed is true, then several thousand others survived to continue the fight.