Italian politicians have complained that David Cameron did not consult their government before approving a failed bid to rescue a British and an Italian held hostage in Nigeria.
Chris McManus, 28, from Oldham, Greater Manchester, and Franco Lamolinara died in the attempt by UK Special Forces and Nigerian military on Thursday.
The UK prime minister said the men’s lives had been in “imminent danger”.
The engineers, abducted last May, were held by an Islamist group in Sokoto.
BBC reporter Haruna Shehu Tangaza in Sokoto said the house where the men were being held had been under surveillance for some time.
He described several hours of heavy fighting and said he also saw the bodies of two Nigerians.