The family of murdered American journalist James Foley says it was threatened by a US official with terrorism charges if they paid a ransom to his captors in Syria. 

Foley's mother Diane told ABC News on Friday that a military officer working for Barack Obama's National Security Council had told them several times that they could face criminal charges if they paid a ransom. 

"We took it as a threat and it was appalling," she said. "Three times he intimidated us with that message. We were horrified he would say that. He just told us we would be prosecuted. We knew we had to save our son, we had to try."

Three times he intimidated us with that message. We were horrified he would say that.

Diane Foley, James Foley's mother.

"We were just told to trust that he would be freed somehow, miraculously,"
Foley's mother said on CNN. "And he wasn't, was he?"

The president's spokesman refused to discuss conversations that the family had with officials, but said they involved people from different government branches.

"I'm not going to get into who said what in the context of these individual conversations," spokesman Josh Earnest said, but he reaffirmed the US policy not to pay ransoms because it could encourage further abductions.

The National Security Council was quoted as saying that the Foley family was informed of US laws banning terrorism financing but denied the family was told they could face charges if they made a ransom payment.

John Kerry, the US secretary of state, said he was "taken aback" by the report. "I am totally unaware and would not condone anybody that I know of within the state department making such statements," he said.

James Foley was beheaded on video by an Islamic State fighter last month. Two weeks later a similar video showed another American journalist, Steven Sotloff, being beheaded.

The US mounted an unsuccessful military mission to try to rescue Foley and other hostages held by the group in Syria this summer.

Source: Agencies