The video released by the Islamic State appears to show US journalist James Foley being beheaded by someone with a 'London accent'. YouTube

The Islamic State militant who apparently beheaded US journalist James Foley in a graphic video released to YouTube last night is a Londoner, a voice expert has claimed.

In the video, a masked man speaks in English with an English accent before killing Foley, who was captured by Syrian militants in November 2012.

Claire Hardaker, a lecturer in Linguistics and English Language at Lancaster University, has told London radio station LBC that his southern vowels place him in the south of the country.

She said on air this morning: "We seem to have definitely southern vowels and some interesting pronunciations.

"We're definitely looking at a British accent, from the south and probably from London."

Foreign Secretary Philip Hammond has revealed that UK authorities are making attempts to identify the IS militant in the video.

He said: "It's been widely reported that he has a British accent...But I can't absolutely confirm that he's British."

Hammond added the incident is yet another example of the brutality of IS, saying: "These people are fanatics with an absolutely abhorrent ideology and a cruelty which we've seldom seen anywhere else in the way they've carried out their actions."

In the video, Foley was seemingly forced to read a statement that blamed America's attacks on Iraq for his death.

The photojournalist said: "I call on my friends, family and loved ones to rise up against my real killers – the US government."

Foley has reported extensively across the Middle East, working for the US publication Global Post and other media outlets including the French news agency AFP.