A man has denied taking part in a brutal knifepoint robbery on a beach.

Kai Griffiths claimed he confronted Stephen Harrison after he allegedly tried to sell Ecstasy tablets to girls aged 13 and 15.

Griffiths admitted punching Mr Harrison during a scuffle on Brighton beach but denied producing a knife or threatening to cut his stomach out.

Mr Harrison, 28, who has a degenerative brain disorder and is considered vulnerable, was allegedly robbed of £245 social security money.

Griffiths is claimed to have encouraged Jamie Pearce, 25, to slit Mr Harrison's throat during the incident in July, 2004. Both men are said to have targeted the alleged victim after seeing him pay for a bottle of water at an all night store near Brighton station with a £20 note.

Walton Hornsby, prosecuting, had alleged that they marched Mr Harrison down to the beach where he was attacked and robbed.

Griffiths, 26, told Lewes Crown Court yesterday he and his friends got off the train from Portslade and were approached by Mr Harrison outside Budgens next to Brighton station. He said: "He offered Ecstasy pills to some of the girls and I told him to leave it out because they were only 13 and 15."

Phillip Wakeham, defending, said to Griffiths: "He says you produced a knife and held it to his stomach and then forcibly marched him down Queens Road to the beach."

Griffiths replied: "He is clearly mistaken. That is not true."

He added Mr Harrison was not with them as they walked down Queens Road and the next time he saw him was on the beach.

A short time later he was told Mr Harrison had allegedly given Ecstasy pills to some of the girls in the group and that is when the scuffle took place.

Griffiths said: "I did not use a knife or any other weapon on him at all or threaten to slit his throat. That is not true."

Griffiths, of North Road, Portslade, and Pearce, of Brunswick Terrace, Hove, both deny robbery.

The trial continues.