Killer property tycoon Nicholas Hoogstraten has accused Tony Blair of briefing security chiefs to frustrate his bid for freedom.

Hoogstraten, in a Category A wing at Belmarsh prison for the manslaughter of a business associate, says he has been prevented from seeing his lawyers and was yesterday banned from speaking to them by phone.

He believes he should be transferred to a lower-security prison but is being kept locked up because of Government worries about links to Zimbabwe.

His claims have been denied by the Home Office and were dismissed as "veering into the realms of fantasy" by Government sources.

Hoogstraten, 58, from Framfield, near Uckfield, is appealing against his conviction last July, which followed the murder of Surrey landlord Mohammed Sabir Raja.

He was jailed for ten years for the killing of Mr Raja, who was shot and stabbed to death by two hitmen.

Hoogstraten was given leave to appeal in March this year but a later application for bail was thwarted.

His legal representative, Giovanni Di Stefano, last night accused the Prison Service of violating his client's rights.

He claimed orders for the treatment of Hoogstraten had come from Mr Blair and Home Secretary David Blunkett.

Mr Di Stefano said: "Every time Hoogstraten wins an action in either the criminal or the civil appeal, the Prison Service hinders access to our client."

He said Hoogstraten's solicitor, Paul Martin, had arranged to visit him in prison on Wednesday this week but was told no booking existed and was turned away at the door.

Hoogstraten was told yesterday phone access to his lawyers had been temporarily prohibited.

Mr Di Stefano said: "It is very clear the Prison Service is acting in close proximity to the Government, who in my view, think that Hoogstraten should stay locked away for as long as possible owing to his alleged links to Zimbabwe.

"They are becoming each day bullies and thugs, not in a physical manner by psychologically. The Prison Service are using their sheer strength and force to ensure he is prejudiced in each and every way.

"Hoogstraten is a precise person and when told he has a visit he expects one, not at the whims and fancies of the prison directorate who are taking orders from political figures.

"I know as a fact the Secretary of State for the Home Department and No.10 Downing Street have given orders via the security services as to how our client is treated and it must stop now."

Hoogstraten was barred from seeing Mr Di Stefano in jail last September because his Belmarsh governor believed they would discuss plans to export fighter planes to Zimbabwe.

However, the High Court later overturned the ban.

Mr Justice Jackson agreed Hoogstraten's human rights had been violated under EU law.

It is believed Home Office doubts about Italian-born Mr Di Stefano's status as a lawyer have prevented him from having unfettered access.

A Home Office spokesman said: "Anyone who is recognised as a bona fide legal adviser by the Law Society may enter a prison to see their client.

"If they do not meet this requirement they cannot enter as a lawyer but can still apply to visit someone in prison.

"Prisoners may have phone contact with their lawyers but again, they need to be a bona fide lawyer, recognised by the Law Society.