George Howarth said the government could not respond to blackmail and would consider in its own time setting up a Royal Commission on whether animal experiments should be allowed

He said there had been "discussions" between Mr Horne's supporters and Home Office officials on his call for a commission.

But he added: "I would not want to leave anybody with the impression that we are in some sort of negotiating situation of some kind. We are not.

"It would be totally inappropriate in this sort of circumstance to negotiate government policy alongside any action that anyone, Mr Horne or anyone else for that matter, takes."

Horne, who is serving an 18-year prison sentence for arson, has gone blind and lost nearly half his body weight.

He is said to be in a "stable" condition in York District Hospital but a spokeswoman said his health "continues to give cause for concern".

To his supporters maintaining a constant vigil at the hospital, Horne is a martyr.

Barry Horne's health is getting worse

To those who suffered from his two-year fire bombing campaign, he is a terrorist.

"Labour can save him," said supporter Alison Lawson. "All they have to do is implement their Royal Commission which was promised before the election and they can save him."

Horne was jailed for causing millions of pounds' worth of damage in arson attacks on the Isle of Wight. He was finally caught planting bombs in Bristol shops two years ago.

Death threats

Police are expecting more violence if he dies and 10 people involved in animal experimentation have already received death threats.

Dr Mark Matfield of the Research Defence Society, said: "I can't see a case for a Royal Commission because the government already has a committee which is looking at this issue of animal experimentation and has been for the past 12 years.

"It has year on year produced recommendations and changes which have benefited animal welfare in laboratories.

"A Royal Commission by comparison would not be able to produce a report for another two or three years."

'Democracy is the only way'

Michael Foster, the Labour MP for Worcester whose Bill to ban hunting with dogs failed in the last session of Parliament, urged Mr Horne to abandon his hunger strike.

He told BBC Radio 4's Today programme: "If we want to get animal welfare legislation through both houses of Parliament, the way to do it is through parliamentary democracy.

"I don't think things can be achieved through activities such as hunger strikes."

Some animal welfare groups have criticised Horne for using "emotional blackmail" which could prove counterproductive.

Jonathan Owen, of the World Society for the Protection of Animals, said Horne's actions could harm the image of animal welfare groups using legitimate means of protest.

"We campaign in a totally different way and are worlds apart from Mr Horne," he said. "We use reason and persuasion - not emotional blackmail or illegal actions."

The authorities are planning to move Horne to a more secure hospital because the authorities are concerned by demonstrations organised by his supporters.