The flak jacket worn by Sergeant Steven Roberts was destroyed shortly after his death in the Iraq war, it emerged today.

The Ministry of Defence confirmed that the Kevlar protective vest Sgt Roberts was wearing was destroyed soon after "because of the potentially hazardous nature of the bloodstains".

But an MoD spokesman said the destruction of the vest would not impede an ongoing investigation into the death of Sgt Roberts - who was the first British soldier to be killed in combat. His widow Samantha Roberts, of Shipley, has given Defence Secretary Geoff Hoon "one last chance" to explain why her husband was ordered to hand back body armour fitted with ceramic plates - which an MoD report said would have saved his life.

Mrs Roberts, 32, spent an hour meeting Mr Hoon yesterday but he resisted calls to resign and refused to accept personal responsibility for Sgt Roberts' death. The tank commander was shot dead trying to quell a riot near Basra on March 24 last year.

He had been ordered to hand back his enhanced body armour because there was not enough to protect infantry troops.

After the afternoon meeting, Mrs Roberts said Mr Hoon "should consider his position". She said her treatment by the Ministry of Defence while trying to glean facts about why her husband did not have enhanced body armour was "disgraceful". But she pledged to give Mr Hoon - who displayed "humility", she said - "one last chance" to prove he was determined to ensure the tragedy of her husband's death was not repeated.

"She said: "There is a long way to go. I don't feel any better about the situation, but perhaps this is one last chance to put right a terrible wrong."

Mr Hoon has promised to put in place an asset-tracking system so the Ministry of Defence can locate each piece of military equipment. He is studying whether enhanced combat body armour - flak jackets containing ceramic plates - could become standard issue to all personnel.

Speaking at a press conference after her Whitehall meeting, defiant Mrs Roberts said: "Mr Hoon has not accepted responsibility but we have assurances that lessons are going to be examined closely. I think he should consider his position very seriously. Mr Hoon is the Secretary of State. He is responsible for the armed forces. If you are a manager of a company, you are responsible for your staff."

Mrs Roberts said the Defence Secretary apologised that her husband did not have life-saving enhanced combat body armour. But she said: "He was very quick to tell us that enhanced combat body armour is not mandatory, which I find staggering."

Mr Hoon has invited Mrs Roberts - who was flanked at the meeting by Sgt Roberts' mother Marion Chapman, brother Tristram Tancock and Cornwall North MP Paul Tyler - to a third face-to-face meeting. This will take place when an investigation into the circumstances surrounding Sgt Roberts' death is completed.