The Washington sniper has left a new note for police - demanding £6.5m.

A handwritten letter in broken English was found close to where bus driver Conrad Johnson was gunned down in Montgomery County, Maryland, on Tuesday morning.

Ballistics tests yesterday confirmed the killing was linked to the sniper.

The new communication follows a rambling letter for police left near the wounding of a 37-year-old man in Ashland, Virginia, on Saturday night.

The note included a chilling warning that children in the area were not safe "anywhere, at any time".

It also criticised the authorities' handling of the case, and detailed at least six failed attempts by the self-professed sniper to reach investigators by telephone since the attacks began.

The writer said his attempts to communicate were not taken seriously by people answering the police line, the Washington Post reported.

It listed half a dozen calls that had been "ignored" by operators at the command centre in Rockville, the Montgomery County police station and the FBI.

The writer reportedly used phrases like "Just shut up and listen" or "Hear me out" or "I am God" or "I'm in charge".

He said "five people had to die" because the operator hung up, said to one law enforcement source.

The note also demanded that authorities put ten million dollars (£6.5m) in a bank account. It gave a deadline of Monday for the money to be deposited.

Ten people have been killed and three people wounded by the sniper since the shootings began on October 2.

Anxious parents yesterday took youngsters to schools in the area which remained open despite the killer's threat against children.

Classroom doors were bolted shut and shades covered windows as pupils were kept indoors until home time. Armed police also guarded many of the schools in the Washington metropolitan area, which serve 700,000 pupils.