BRITISH forces do not know where aid worker Alan Henning is being held hostage, Foreign Secretary Philip Hammond has said.

Threats to kill the 47-year-old former taxi driver — who travelled from Bolton to Syria in December last year — were made at the end of a video showing the brutal murder of British aid worker David Haines.

Mr Hammond said: “If we knew where he was, we would be able to look at all sorts of options but we don't know where he is.

“We have considered every possible option to support these kidnap victims.”

Mr Hammond said Mr Henning's family was “going through hell” but that they understood there was a limit to what the Government could do to help him. He added: “It is a terrible time for them. We are doing everything that we can to protect him.

“They understand, because we have explained to them in detail, the limitations of our abilities. We are dealing with a very barbaric organisation whose values are completely different from ours.”

Mr Henning's sister, Gill Kenyon, from Bury, posted a picture of the pair together as children on social media, to mark his 47th birthday in August.

The message said: “Happy 47th birthday to my little bro Gadget/Alan Henning. Can’t wait to have a party on your return, love you bro xx.”

Mr Henning, from Eccles, twice travelled from Bolton to Syria — in March and December last year with eight other volunteers from Bolton alongside the UK Arab Society.

Kasim Jameel, who travelled with Mr Henning to Syria, described him as an "amazing guy" and said he was praying for him.

He has been described as a “passionate volunteer” who “took that extra risk” to deliver aid.

Colleagues nicknamed him “Gadget” and praised his sense of humour.

It is understood Mr Hennning was captured just 30 minutes after he arrived in Syria in December 2013.