The masked Islamic State militant known as "Jihadi John", who has been pictured in the videos of the beheadings of Western hostages, has been named.

The BBC reports that he is Mohammed Emwazi, a British man believed to be from West London, who was known to British security services.

They chose not to disclose his name earlier for operational reasons.

Emwazi first appeared in a video last August, when he apparently killed the American journalist James Foley.

He was later thought to have been pictured in the videos of the beheadings of US journalist Steven Sotloff,  British aid worker David Haines, British taxi driver Alan Henning, and American aid worker Abdul-Rahman Kassig, also known as Peter.

Last month, the militant appeared in a video with the Japanese hostages Haruna Yukawa and Kenji Goto, shortly before they were killed.

Emwazi is believed to be an associate of a former UK control order suspect, who travelled to Somalia in 2006 and is allegedly linked to a facilitation and funding network for Somali militant group al-Shabab.