The documents contain more than 70 records of so called "Green on Green" incidents in which Afghan security forces have fought each other rather than the Taliban.

One report, on the shootings of a logistics officer and an Afghan intelligence officer in February last year, says that two Afghan policemen were "conducting horseplay with their service arms when they accidently shot the NDS director... and logistics officer."

Deliberate attacks

That incident was accidental, but the documents also describe episodes where Afghan security personnel have turned their weapons on each other in anger, often as a result of disputes between the army and the police.

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Fighting takes place within individual units as well. In April 2009 British troops reported that an Afghan soldier had shot his sergeant following an argument, and in another incident, a firefight between Afghan forces left a local civilian boy with a gunshot wound in his stomach.

Martine van Bijlert, co-director of the Afghanistan Analysts Network, said that the reports were no surprise.

"There have been regular cases of local fights between the army and the police, or internally between army or police units," she said.  

"It's part of the current nature of the Afghan security forces; partly a lack of discipline, small disputes that get out of hand. And sometimes there are pre-existing conflicts that come to a head, particularly between local forces."

Drug abuse

Some of the violence occurs after heavy drug use amongst Afghan forces. US troops have told Al Jazeera that some Afghan soldiers are smoking large quantities of marijuana before going out on patrol, leaving them unable to concentrate and suffering from repeated fits of "giggles" as they move through Taliban-held territory.

One incident described in leaked documents records how a gunfight broke out between Afghan border guards who "were high on opium and having a party," on the roof of an interpretor's accomodation.

The guards awoke the interpretor and an argument broke out. In the ensuing gun battle one of the guards was killed after being shot in the stomach.

Another problem revealed by the documents is the high rate of desertion. The records show that at least 20 Afghan policemen deserted from a single post last summer, stealing vehicles in seperate incidents a fortnight apart.

Van Bijlert says some of the equipment taken during desertions has ended up in the hands of the Taliban.

"There have definitely been reports from the field of desertions where equipment is taken, in some cases the guns and cars are handed over to the insurgency," she said, adding that Karzai's timetable for Afghan forces taking control could be affected by the release of the information.

Timetable affected?

"There is a danger with tight timetables that the picture is made rosier than it is, in order to argue that things are on track. That might have become a bit harder, now that these documents are out there. They don't just show how things are, but also what the military and the administration knows."  

More than $27 billion has been invested in Afghan security forces and revelations will come as a major concern to countries with troops in Afghanistan, many of whom have endorsed Karzai's handover plan.

David Cameron, the British prime minister, has explicitly linked the outcome of the war with the degree to which Afghan security forces are able to take responsibility for the country.

"Victory in this war is being able to hand over to an Afghan government and an Afghan army and police force that are capable of securing their own country," he said last week.