A Home Office spokesman declined to comment as it was ‘operational issue’.
It came as it emerged the police officer who made an internet jibe about G20 victim Ian Tomlinson has resigned.
Pc John Hayter, 49, a member of the Royal protection unit, stepped down after an internal inquiry was launched.
Investigators were probing claims he wrote on Facebook: “I see my lot have murdered someone again. Oh well, s*** happens.”
A second Metropolitan Police officer Rob Ward, 27, remains under investigation for posting separate online comments in which he said he wanted to “beat up some long-haired hippies” in a message on a Facebook page.