Shadow Defence Secretary Liam Fox has demanded a government apology over the "unnecessary" death of a soldier.
Sgt Roberts was the first British soldier killed in action in Iraq
A coroner said Sergeant Steven Roberts had been shot dead in Iraq in 2003 because of "inexcusable" delays in providing body armour to troops.
In a letter to Defence Secretary Des Browne, Dr Fox blamed "political expediency" and called for a public apology to Sgt Roberts' widow Samantha.
The government has promised to look at the findings of Monday's inquest.
Mrs Roberts' solicitor Geraldine McCool said her client had been promised an apology by the Ministry of Defence after the inquest was completed.
"I very much hope that in the New Year Samantha and the Roberts family will receive the apology that they very much deserve," she told the BBC.
Sgt Roberts, 33, from Shipley, West Yorkshire, was shot dead in a "friendly fire" incident as he manned a checkpoint. He was the first British soldier killed in action in Iraq.
He had been ordered to give up his enhanced combat body armour three days previously, due to shortages.
The inquest heard delays supplying the £167 piece of kit had meant more than 2,000 soldiers had gone into combat without it.
An Army Board of Inquiry into Sgt Roberts' death found that the pistol he tried to shoot the Iraqi with had failed and he was shot by a comrade in a tank who was trying to protect him but did not know his high-powered machine gun was inaccurate at short range.
In his letter, Dr Fox said an urgent requirement had been "directed to the secretary of state but no action was taken for eight weeks on the issue of body armour".
He added: "As the board of inquiry put it: 'it must be understood that the deployment timeline had been severely compressed due to political sensitivities over overt military operations'.
"In other words, despite the likelihood of military conflict with Iraq, the government's duty of care and their obligation to minimise the risk to our armed forces played second fiddle to political considerations.
"The argument put forward by the MoD [Ministry of Defence] that the procurement of the necessary quantity of body armour would have sent the wrong signal to the Iraqi regime is nonsensical.
"Why not apply the same argument to ammunition, rifles, or tanks?"
The MoD has said it recognises that supply failures had contributed to Sgt Roberts' death.
In his letter, Dr Fox said: "The fact remains that Sergeant Roberts died unnecessarily as a result of political expediency.
"I fully understand that you [Mr Browne] were not secretary of state at the time of these events and had no personal responsibility for them.
"Nonetheless I feel very strongly that the government in general and the MoD in particular should offer a public apology to the widow of Sergeant Roberts and to all those who may have been killed or injured as a result of this fundamentally wrong approach to procurement in the run up to the Iraq war."
Liberal Democrat trade and industry spokesman Lord Lee said the MoD should not be exempt from the offence of corporate manslaughter, which is currently being considered by Parliament.
He added: "The conclusion yesterday of the coroner's inquest into the death of Sgt Roberts in Iraq shows there is a real need to hold the MoD to account over the failure to provide a duty of care to soldiers.
"It is shocking that the Ministry of Defence is sending troops into conflict situations and endangering their lives without the adequate kit."
Oxfordshire assistant deputy coroner Andrew Walker recorded a narrative verdict - which simply records the circumstances surrounding the death - at Sgt Roberts' Oxford inquest.