Two men being held hostage by al-Qaeda have been killed in an American anti-terror operation.

The White House has confirmed Dr Warren Weinstein, from the US, and Giovanni Lo Porto, from Italy, both died in the raid.

They had been held captive by the group in the border region of Afghanistan and Pakistan since 2011.

An American al-Qaeda leader was also killed.

The White House said in a statement: "Analysis of all available information has led the Intelligence Community to judge with high confidence that the operation accidentally killed both hostages".

It is also believed that two other Americans were recently killed in US counterterrorism operations in the same region.

Ahmed Farouq - an American who was an al-Qaeda leader - was killed in the same operation that resulted in the deaths of Dr Weinstein and Mr Lo Porto.

While Adam Gadahn - an American who became a prominent member of al-Qaeda - was killed in January, likely in a separate US operation.

"While both Farouq and Gadahn were (al-Qaeda) members, neither was specifically targeted, and we did not have information indicating their presence at the sites of these operations," the White House added.

The statement adds that the US government had spent years trying to locate and free Dr Weinstein and Mr Lo Porto.