Talks 'failed to save Islamic State hostage Kassig'
Details have emerged of an attempt to secure the release of kidnapped US aid worker Abdul-Rahman Kassig before he was killed by Islamic State militants.
A US lawyer told the BBC he persuaded two radical Muslim clerics in the Middle East to make contact with IS.
But the talks broke down when one of the clerics was arrested in Jordan for promoting jihadist views, he said.
The FBI has confirmed to the BBC that it was aware of the discussions, but refused to elaborate.
New York lawyer Stanley Cohen said he was asked to help by a US veteran and Palestinian activists who knew Mr Kassig. He was known as Peter before he converted to Islam while in captivity.
Mr Cohen, who has represented Hezbollah, Hamas and the son-in-law of Osama Bin Laden, said he discussed his plans with the FBI before travelling to Kuwait and Jordan as a private citizen.
Abdul-Rahman (aka Peter) Kassig
- Former US Army Ranger
- Served in Iraq in 2007
- Travelled to Lebanon in May 2012, volunteering in hospitals and treating Syrian refugees
- Founded aid organisation Special Emergency Response and Assistance (Sera) in 2012 to provide aid to Syrian refugees
- Captured by Islamic State in October 2013 while travelling to Deir al-Zour in eastern Syria
- Converted to Islam in 2013, changing name from Peter Kassig
There, he says he met clerics with links to al-Qaeda, and persuaded them to intervene on behalf of Mr Kassig.
One of them - Abu Mohammed al-Maqdisi, the spiritual leader of the Jordanian Salafist-jihadist movement - began sending messages to Islamic State leaders.
But he was arrested by the Jordanian government for using the internet to promote jihadist views, and the talks subsequently broke down.
The other cleric was reportedly Abu Qatada, who was released from prison in Jordan in September after being found not guilty of terrorism offences by a court in Amman.
He confirmed in an interview with the Guardian newspaper that he had he worked with Abu Mohammed al-Maqdisi to help save Mr Kassig.
Mr Cohen said negotiations with Islamic State, formerly known as Isis, had been "sandbagged by the Jordanian government".
"The bottom line is this: it wasn't Isis that broke the agreement although Isis did, in fact, kill Kassig," Mr Cohen told the BBC's Newsday programme.
"The agreement was broken by Jordan and the US did nothing to undo it. I went to the Middle East with the assurances from Isis that come - that he'll remain alive - we'll listen to you and we'll see where this goes and for six weeks he remained alive."
The Jordanian government has not commented on the allegations.
Mr Cohen is due to begin a prison term next month for tax offences.
A former US ranger, Mr Kassig, 26, founded a humanitarian organisation to help refugees fleeing from Syria's conflict.
He was captured by Islamic State in October 2013 while travelling towards to Deir al-Zour in eastern Syria. The group announced his death on 16 November with a grim video showing the aftermath of his decapitation.