WASHINGTON: President Barack Obama on Thursday said he takes “full responsibility” for a counter-terrorism operation on the Pakistan-Afghanistan border that inadvertently killed an American and an Italian hostage held by Al Qaeda.

Obama said he profoundly regretted the deaths of Warren Weinstein, an American national, and Giovanni Lo Porto, an Italian national.

“As a husband and as a father, I cannot begin to imagine the anguish that the Weinstein and Lo Porto families are enduring today,” Obama told reporters, with a deep sigh, saying he took responsibility for the deaths and has ordered a full review.

The president said the men were killed during a mission that targeted an Al Qaeda compound in the border region between Afghanistan and Pakistan.

He said the January mission was “fully consistent” with guidelines for conducting counter-terrorism missions in the region, adding that there was no information showing the hostages were being held at the Al Qaeda compound.

Read: US citizen kidnapped from his Lahore residence

Weinstein, a 73-year-old development worker, was abducted in August 2011. His capture came four days before his seven-year stint with the US Agency for International Development was to end.

Warren Weinstein.- DawnNews screengrab

In a message released previously in English and Arabic and addressed to Weinstein's family, Al Qaeda had said it was “not interested in keeping” Weinstein but wanted to exchange him for prisoners in US custody.

Lo Porto was an Italian aid worker who worked for the German aid group Welthungerhilfe. He went missing in Pakistan in January 2012.

A spokeswoman for the aid group said the organisation was shocked at the news of Lo Porto's death. “We're shattered by today's news,” Simone Pott told The Associated Press. “So much was done to try and get him released,” she said, without elaborating.

Lo Porto had joined the aid group in October 2011 and was working as a project manager in Pakistan's Multan region when he was kidnapped together with German national Bernd Muehlenbeck.

Muehlenbeck was freed last year under circumstances that Pott declined to comment on.

Also read: German aid worker kidnapped in Pakistan freed in Afghanistan

Italian Prime Minister Matteo Renzi expressed his “profound pain” over Lo Porto's death, saying the aid worker had “dedicated his life to the service of others".