The four, who were arrested over the past two weeks, are variously charged with obtaining a handgun and conducting "hostile reconnaissance" of Shepherd's Bush police station in west London and the nearby White City reservist army barracks.

Further charges include storing images sent via photo-sharing service Instagram of two police officers and of two civilian police community support officers.

"This is a plot, in essence, to shoot, to kill, police officers or soldiers on the streets of London," prosecutor Mark Dawson told Westminster Magistrates' Court.

Tarik Hassane, 21; Suhaib Majeed, 20; Nyall Hamlett, 24 and Momen Motasim, 21, all from the London area were remanded in custody after a brief hearing to appear at the Old Bailey court on Oct. 27.

They have yet to enter a plea. The charges variously laid against them also include setting up methods of secret communication and possession of extreme terrorist’s material which included footage of the beheading by IS of American journalist Steven Sotloff last month.

A fifth man, Nathan Cuffy, 25, also from London, was remanded in custody on firearms offences.