Defence Secretary Geoff Hoon was yesterday facing mounting calls to resign over the case of a soldier shot dead in Iraq soon after he was ordered to hand back his body armour because of shortages.

Sergeant Steve Roberts, 33, had told his wife at home of his worries about being sent into battle without proper equipment and body armour, describing the situation as a joke.

The tragedy yesterday developed into a political row, with Prime Minister Tony Blair questioned over the issue amid calls for his minister to resign.

Mr Hoon was told to quit by Tory leader Michael Howard after the soldier's widow revealed an audio tape diary kept by Sgt Roberts where he spoke of troops' lack of equipment.

Sgt Roberts, who was serving with the 2nd Royal Tank Regiment in Iraq, had been told to hand back his flak jacket because there were not enough to go round.

Days later, on March 24 last year, he was killed trying to quell a riot in Zubayr, near Basra.

Sgt Roberts, from Shipley, near Bradford, West Yorkshire, made the audio diary of his time in Iraq to send back to his wife, Samantha. They were given to her at his funeral.

During the tapes, he spoke of his fears at the lack of proper equipment. In his final message he told his wife he loved her. He was killed the next day.

Mr Howard yesterday backed calls by the widow of Sgt Roberts for Mr Hoon to resign.

"I do not think there is any greater dereliction of duty for any government than to send men into battle without the proper equipment," he said.

"That is clearly what happened here, we know it is what happened.

"We know that the probability is that Sergeant Roberts would not have been killed if he had had body armour. We know that he was asked to give his body armour to another soldier who was assumed to be at greater risk and we know the Government lost 200,000 pieces of body armour, which could - and should - have been made available to our troops in the Gulf.

"It is a very serious state of affairs. I entirely agree with Mrs Roberts in her request that Geoff Hoon should resign."

In the series of tapes to his wife, Sgt Roberts spoke of his own fears.

"Things we have been told we are going to get, we are not," he said. "It's disheartening because we know we are going to go to war without the correct equipment.

"It fills me with remorse really and I think remorse is the right word because I know we have received our orders."

He said: "We are now back into one of the camps to up-armour, which again is a bit of a joke in itself because they are running out of the frontal armour.

"It will be interesting to see what armour I actually get. I will keep you posted."

Mr Hoon this week dismissed allegations of inadequate supplies of body armour and weapons while under questioning in the House of Commons.

Mrs Roberts, 32, who revealed the tapes public to highlight the plight of soldiers, said her husband wished her a final emotional "good night" at the end of one of his recordings.

"It (the tape) was very emotional. There was quite a lot of emotion in his voice," she said.

"He had left me a tape with my father-in-law, before he left for Iraq, in the event that anything happened to him. But I had not heard his voice since he'd died until I played these tapes.

"I'm pleased I've got them. They were very upsetting when I first heard them, but I've listened to them hundreds and hundreds of times now. He was quite nervous about the situation he found himself in."

Sgt Roberts' final words to his wife were: "I love you lots. Sleep tight, babe. Bye."

He was buried with a full military funeral in Harrogate.

A Ministry of Defence inquiry has been launched into his death. The MoD said yesterday such investigations were a private internal matter and the results would not be made public.