The family of a man shot dead by police who mistook him for a suicide bomber have reacted angrily to reports that a "dum dum" style bullet killed him.
Jean Charles de Menezes was shot seven times in the head
Hollow point or dum-dum bullets, which expand and splinter on impact, killed 27-year-old Jean Charles De Menezes, the Daily Telegraph claims.
His cousin Alex Pereira said: "I am shocked and angry. I had no idea."
The Metropolitan Police would not say if the bullets were used. There is no ban on police using such ammunition.
Dum dum bullets were invented in the 19th Century by the British in India and outlawed in warfare under the Hague Declaration in 1899.
The Met also said it would not comment specifically on the Menezes case while an investigation by the Independent Police Complaints Commission (IPCC) was being carried out.
"We have a range of weaponry and ammunition which we use as appropriate to operational circumstances," a spokesman said.
Hollow point bullets were available to officers working in Operation Kratos - by which the policy of shooting suspected suicide bombers in the head is known - according to the Telegraph.
Their use was given the go-ahead after research suggested they were effective at close-quarters against someone about to trigger a suicide bomb, it claims.
They have been assessed as posing less risk to people around the suicide bomber that conventional bullets, but for the person shot they are much more deadly.
Like the shoot-to-kill policy itself, the decision to make such bullets available to officers was taken in secret.
Mr Pereira, a cousin of the Brazilian electrician, said: "If they [police] break international law they should be punished.
"How can the police in the UK use bullets that the army is not allowed to use? The police need to be open about what they are doing and if they act illegally they should be punished."
He repeated his family's calls for those responsible for the death to be brought to justice.
"If David Blunkett was made to resign when he misled the public why doesn't the same apply to the police who were responsible for killing my cousin?" he said.
The shooting of Mr Menezes came the day after the failed London bomb attacks of 21 July.
He was shot seven times in the head by anti-terror officers while passengers looked on at Stockwell Tube station.