The US Supreme Court has turned down an appeal to postpone the execution of sniper John Allen Muhammad who killed ten innocent civilians in Washington and the states of Maryland and Virginia seven years ago.

Mr Muhammad carried out the killings over a three week period together with a teenage accomplice Lee Boyd Malvo, who is currently serving a life sentence.

The sniper's lawyers argued that their client was not given a proper trial and should never have been allowed to conduct his own defence because he was suffering from mental health problems.

The court rejected their arguments and Mr Muhammad is due to receive a fatal injection at a Virginia prison later today.