"I am 100% sure they were military," he said. And there was little hope of police collaring the culprits. "The police are working with the thieves, I am sure."

Laura Bush's surprise appearance in Kabul yesterday signalled growing US confidence in Afghanistan's once-precarious security. The Taliban insurgency is waning, military commanders claim, boosting reconstruction efforts.

But ordinary Afghans, alarmed by a swelling crime wave, see it differently. Armed robbery, kidnapping and intimidation have displaced the Taliban as the principal security problem. The line between cops and robbers is becoming increasingly blurred.

Although no official statistics are available, the perception of a worsening situation is widespread. Frustration boiled over in the southern city of Kandahar this month when thousands of men took to the streets to protest at a spate of kidnappings that left at least one child dead.

Calling for the resignation of the governor and police chief, the crowd smashed shop windows and destroyed several vehicles. Days later, the Kabul government transferred the provincial security commander to another area.

Demobilised Mujahideen fighters, underpaid policemen and corrupt officials are behind the lawlessness, according to Afghan officials, western diplomats, and victims.

Three Scotland Yard detectives flew back to Britain this week after inquiries into the death of Stephen MacQueen, the British consultant shot in his car in Kabul on March 7.

By contrast with the US-led training of the new Afghan army, the 38,000-strong police force is considered a failure by diplomats and other officials.

Scanty training and poor wages are part of the problem. Judge Abdulbaset Bakhteyari said his children had been detained for several hours recently after police pulled their driver over to seek a bribe.

"Officers have no faith in the future so they work for their own benefit," said Judge Bakhteyari, who works with AK-47 propped against the wall behind his desk.

Thousands of newly demobilised mujahideen fighters have been inducted into police ranks. Many have retained their criminal sidelines.

The crime wave has heightened worries that a culture of impunity has taken root in the Karzai administration.

Several aid officials, requesting anonymity, said they believed a senior police officer was behind the killing of five Médecins sans Frontières (MSF) aid workers last June, which prompted the agency to leave Afghanistan. The officer concerned has retained his job.

Earlier this month two Afghan aid workers were killed in the western Farah province, allegedly by renegade police officers.

When angry relatives protested to the provincial police chief, his bodyguards opened fire, killing one.

Western officials have pressed the interior minister, Ali Ahmad Jalali for reforms. Last weekend, he announced a shake-up of the police.

Yet the Karzai government's greatest crime challenge may lie further up the ladder. Gleaming buildings sprouting up around Kabul are seen as testament to the heroin trade, which accounts for over 40% of the Afghan economy. Not one major smuggler has been prosecuted.