The timing of the award is almost as striking as the writing which it honours. A former American machine gunner's memoir of a year's tour of duty in Iraq based on his blog has just won a major accolade at precisely the moment when the US military high command is clamping down on blogs among the rank and file.

Colby Buzzell was awarded the £5,000 Lulu Blooker prize for My War: Killing Time in Iraq, which was voted the best book of the year based on a blog. It triumphed over 110 entries from 15 countries.

The memoir was drawn from a blog he kept while in Mosul, in northern Iraq, in 2004, in which he portrayed the texture of daily life there, from listening to Metallica on his iPod to watching his fellow "grunts" surf the web for pornography.

The paradox of Buzzell's victory is that it quickly follows the revelation that the Pentagon has introduced new rules restricting blogs among soldiers, fuelling speculation that live and unadorned combat writing from the field such as Buzzell's may be the last of its kind.

The new rules require all would-be "milbloggers", as soldier-publishers are called, to submit blog entries to supervising officers before posting them. That turns on its head the existing rules which allowed soldiers to post freely, with the onus on them to register their blogs and to alert officers to any material that might compromise security.

Yesterday the defence department went further and announced it was blocking access "worldwide" to 13 communal websites, including YouTube and MySpace from military computers and networks. General BB Bell said the move was to protect operations from the drain on computer capacity caused by soldiers downloading videos on these sites.

But prominent military bloggers said this was another move by commanders to try and regain control over ue of the internet. Matthew Burden, a former major in the US army who runs the most popular milblog, Blackfive, with 3 million unique users a year, said he had been contacted by several serving soldiers who said they were going to stop posting. "They are all putting their hands in the air and saying, 'That's it, I've had enough.'"

He said the rules were self-defeating and would deter blogs such as acutepolitics@blogspot.com, which is written by a specialist who defuses roadside bombs. "Take that down and you are removing one of the most positive messages for what the army is doing in Iraq," Mr Burden said.

Mr Buzzell, now 30, was sent to Iraq in November 2003. He had joined the army at a time, he said, when "I was living off Top Ramen [pot noodles] in a suburb of San Francisco and my life was going nowhere". He discovered blogging by reading a Time article while in Iraq, and started posting eight months into his tour.

He rapidly built up a huge following and was profiled in the media. After six weeks an order came down that his blog should be stopped, without any explanation; but by then he already had 10 different publishers clamouring after him.

Buzzell said the new restrictions would hurt combat soldiers and their families. "It's hard for them out there, and this will make it harder. It will lower soldier morale for troops who are on their second or even third tour." He also regrets the tightening grip over blogging on a personal level because without it, he said, he would now be "washing dishes in a restaurant somewhere, back to eating Top Ramen".

As it is, his book has been translated into seven languages, and he has embarked on a freelance writing career for Esquire magazine, among others. "This is a totally screwed up policy," he said. "The commanders are just really nervous because they can't keep control any more."

· Extract: My War: Killing Time in Iraq

Thursday August 4 2004

Down in the hatch, I was frantically scanning my sector when suddenly about 300 metres away from us, over by the traffic circle, I saw two guys with those red-and-white jihad towels wrapped around their heads creeping around a corner. They were hunched down hiding behind a stack of truck tyres. I could tell by their body language that something was up. I placed the crosshairs right on them and was about to waste them, but for some reason I didn't pull the trigger. These guys were not dressed in black like the guys earlier and from what I could see they didn't have any weapons on them. Something told me that I should wait for just one, maybe two more seconds. Then I saw another guy come creeping around that corner with an RPG in his hands. As soon as I saw that I screamed as loud as I could, 'RRR-PPPPP-GGGGGGG!!!' into the CVC. My crosshairs were bouncing all over, so I gathered my composure as fast as I could, put the crosshairs on them, and engaged them with a couple of 10-round bursts of some .50-cal, right at them.

Nobody moved from behind those tyres after that.

A couple minutes after that the Stryker that was parked 10 metres in front of us, Bravo 65 Victor, took an RPG that came from a building that looked like a parking garage that was diagonally across the street. It scared the fucking shit out of me when they got hit ... We all pointed our weapons to that building and started lighting it up with everything we had. Bravo 65 immediately reported casualties, "We're hit! This is Bravo 65 Victor! We have wounded!!! We need CAS Evac. Time: Now!" came over the radio.

Lt Armeni, who was inside that vehicle, got severely injured and needed medical attention immediately. The RPG penetrated right through the armour and sliced Lt Armeni's guts completely so that they were hanging out of his stomach ...

I then saw a man, dressed mostly in white, with no weapon on him, run for his life, out of the building, and right in front of our vehicle. I lowered the .50 cal at him and tried three times to hit him, missing him every time. Several other people tried shooting at this guy as well, and somehow the bastard got away.

· Biography: Colby Buzzell

Age: 31

Born: in San Francisco, now lives in LA

Hobbies: skateboarding and hard rock

Job: machine gunner turned author

Started blogging because: 'It sounded like a good way for me to kill some time out here in Iraq, post a little diary stuff, maybe some rants, links to some cool shit, thoughts, experiences, garbage, crap, whatever.'

Literary idols: Kurt Vonnegut and Hunter S Thompson

Favourite sounds before a mission: the Cure, the Smiths "and a little bit of the old school U2"