A Briton and an Italian were killed on Thursday by their Nigerian captors during a failed rescue operation launched by the joint forces of Nigeria and the UK.

British engineer Chris McManus and Italian national Franco Lamolinara were abducted by the gunmen belonging to an offshoot of the Nigerian terrorist group Boko Haram on 12 May, 2011.

According to the Foreign and Commonwealth Office (FCO), the two men were killed in Sokoto, to the north-east of the Birnin Kebbi city from where they had been abducted.

The duo was captured from the MacManus' apartment in North Nigeria.

Prime Minister David Cameron authorised the mission after receiving credible information about the whereabouts of the hostages and since the lives of the hostages appeared to be in danger.

"A window of opportunity arose to secure their release. We also had reason to believe that their lives were under imminent and growing danger," said David Cameron while confirming the death of the two engineers.

"Early indications are clear that both men were murdered by their captors before they could be rescued," he added.

McManus and Lamolinara were working as engineers for an Italian construction company, B Stabilini.

"As a family, we are of course devastated by the news of Chris's death," said MacManus' family in a statement.