A vulnerable 15-year-old brought from London to Norwich to sell drugs was an "all too familiar" part of a county-lines operation, a court heard.

The teenager, who cannot be named for legal reasons, was in Norwich in March and in April, last year, to help deal heroin and crack cocaine in the city, Norwich Crown Court was told.

John Morgans, prosecuting said that the defendant who is now 16, was only 15 at the time of the offence and was arrested on April 3, last year, after officers saw him acting suspiciously around Bishop Bridge Road, in Norwich.

Mr Morgans said that when officers went to arrest him he fled the scene: "He ran off but was detained by the officers."

He said that the teenager was found to be carrying a knife and keys for a property in William White Place, where phones were seized.

He said that drug dealing messages were found on the phones.

Mr Morgans said that three days later the youth was stopped again when he was a passenger in a Mini with false number plates and the driver was found with 34 wraps of heroin and 83 wraps of crack cocaine.

The defendant admitted conspiracy to supply Class A drugs and possession of a bladed article. He also admitted further drugs matters from London and possession of a lock knife and was given a 12 month detention and training order.

Sentencing him, Judge Anthony Bate said his case was an all too familiar example of county line drugs dealing where young vulnerable people were used as "fodder" by those running the operation.

He accepted he played a lesser role.

Tayyiba Bajwa, for the youth, said that he was only 15 at the time and was acting under direction having been brought to Norwich to deal drugs.

She said that he was a bright young man but said that he was vulnerable and naive.

Norfolk police have been working with colleagues in London to try to break the criminal networks known as county lines which target children and vulnerable adults to courier drugs.