Farmer Tony Martin - who has served three years in jail for killing a teenage burglar - has been denied early parole from Highpoint Prison in Suffolk.

Martin, one of 22 prisoners who submitted requests for parole consideration on Thursday, is scheduled for release on 28 July.

James Saunders, Martin's solicitor, said Martin would be "bitterly disappointed and very let down" to hear the ruling from the board, which did not specify why he was turned down.

Mr Saunders said: "He has behaved impeccably whilst inside so it can't be on the basis of his behaviour."

He added: "There has been a suggestion that maybe there is some risk to him if he comes out."

His mother, Hilary Martin, said she was disgusted that her son's early parole had been refused.

She said she believed he would simply keep his head down and serve the remaining months of his sentence.

There has been a suggestion that maybe there is some risk to him if he comes out James Saunders, Martin's solicitor

Henry Bellingham, the MP for North West Norfolk, said he would table an urgent question to Home Secretary Jack Straw.

"I'm staggered, I'm appalled and extremely surprised because Tony Martin was a model prisoner.

"His behaviour was exemplary and I just can't understand for the life of me why the parole board took this decision."

Longtime supporter Malcolm Starr said he believed Martin had not been paroled because he refused to apologise for his actions.

He said: "His pride is at stake and he wasn't prepared to compromise it.

Fred Barras was killed in 1999

"What sort of country are we living in when you have to apologise for defending your own property?

"It is a shocking and lamentable ruling," Mr Starr said.

The farmer has always claimed he acted in self-defence when he shot dead 16-year-old Fred Barras, from Newark, Nottinghamshire, and injured another man with an illegally-held pump-action shotgun in 1999.

They had broken into his near-derelict farmhouse Bleak House, near Wisbech, where Martin had removed part of a staircase to hinder intruders.

Martin's conviction for murder in 2000 caused massive controversy, and raised issues about rural crime and the rights of householders to protect their property.

On appeal Martin's murder conviction was reduced to manslaughter and his sentence cut to five years.