The man accused of the frenzied knife murder of schoolgirl Claire Tiltman told a prison inmate how he "snapped and attacked" someone after seeing them on a zebra crossing, a court heard.

Colin Ash-Smith was said to have added he was angry at the time and "looking for something or someone."

The jury at Inner London Crown Court heard the alleged confession at the start of the third week of the trial in which the 46-year-old former milkman from Swanscombe denies stabbing Claire to death in January 1993.

The 16-year-old died in an alleyway off London Road, Greenhithe, after suffering nine knife wounds.

Ash-Smith was in HMP Wakefield for two knife attacks he committed in 1988 and 1995 when he was befriended by convicted sex offender Stefan Dubois.

The court heard Mr Dubois, who was himself jailed for 12 years, told police last year of a conversation they had had had during a role-play adventure game called Dungeons and Dragons.

In a tense exchange with prosecutor Brian Altman QC, Mr Dubois told the court he could not rely on his memory because of medication he had been taking for the past year.

But, having been shown a copy of his statement and agreeing that he had signed it, he was asked to tell the court what Ash-Smith had told him.

Mr Dubois said: "According to my statement I remember him saying crossing someone on a zebra crossing and snapping and attacking them.

"Either he was crossing the zebra crossing on foot or he was driving past just before it happened."

The jury had already heard that Claire had diverted on her walk from her home in Woodward Terrace, Stone, to her friend's house to buy cigarettes from a shop off Knockhall Chase.

She would have then crossed London Road to continue her journey to nearby Riverview Road.

Mr Dubois was released in 2007 but said he had remained in "infrequent" contact with Ash-Smith via letters, telephone calls and prison visits.

Asked whether he still considered himself to be Ash-Smith's friend he replied: "Absolutely."

At the start of his evidence Mr Dubois told how inmates had "joked" about Ash-Smith not being on the prison darts team.

"It was mentioned either by Colin himself or others that knew him that he stabbed his victim multiple times but missed every vital organ and the joke was we wouldn't have him on the prison darts team."

The pair also talked about the existence of pistol crossbows, to which Ash-Smith told Mr Dubois they did exist and that he had them in his car.

During cross-examination Mr Dubois said he could not remember the context of the zebra crossing conversation and that he may have confused Ash-Smith with another inmate.

The trial continues.