Gordon Brown was confronted over the lack of equipment for British troops by the mother of a dead soldier when he called to offer his condolences.
The Prime Minister was said to have been "mortified" when told of Jacqui Janes' distress over errors in a hand-written letter of condolence, immediately arranging a telephone call to say sorry.
But Mrs Janes confronted Mr Brown in the 13-minute phone, telling him that her son Jamie could have survived his injuries but bled to death, according to a transcript in The Sun newspaper.
"Mr Brown, listen to me," she said.
"I know every injury my child sustained that day. I know that my son could have survived but my son bled to death.
"How would you like it if one of your children, God forbid, went to a war doing something that he thought, where he was helping protect his Queen and country and because of lack, lack of helicopters, lack of equipment, your child bled to death and then you had the coroner have to tell you his every injury?"
Mr Brown said he understood, but had his own strong feelings on the issue and wanted to offer his condolences, rather than interact in a political debate.
At one point in the conversation, Mrs Janes said: "I can not believe I have been brought down to the level of having an argument with the Prime Minister of my own country."
Mr Brown denied spelling Mrs Janes' son's name wrong in the letter, and blamed his poor handwriting rather than his spelling.
But she told him: "I beg to differ."Reuse content