London, Aug 20 (IANS/EFE): British Foreign Secretary Philip Hammond warned Wednesday of the "threats" posed by a "significant number" of Britons working with jihadis in Syria and Iraq, as he condemned the video of the alleged beheading of US journalist James Foley.

Hammond said the hooded man who was speaking in the video appeared to be British, saying "certainly that is what it seems in the beginning and obviously we want to investigate more".

Speaking to the BBC, Hammond said the beheading of Foley by a member of the Islamic State (IS) Sunni extremist group after he was abducted in Syria in November 2012 is "an appalling example of the brutality of this organisation".

He added that the involvement of Britons, who at some point will return to the Britain, with the IS in Syria and Iraq "is one of the reasons why this organisation represents such a direct threat to the Britain's national security".

Britain is working to track British citizens who could be involved in terrorist activities, Hammond said.

In the video posted Tuesday by the jihadis, Foley, 40, said goodbye to his family and accused the US government of being responsible for his execution due to its intervention in Iraq.

After he spoke, a masked militant with a British accent warned the US it was no longer fighting an insurgency but "an Islamic army and a state that has been accepted by a large number of Muslims worldwide" and appeared to cut the hostage's neck as the video fades to black.

The British foreign secretary explained that although the recording has not been verified yet, "all signs prove it as genuine".