With Britain on the brink of war with Iraq, the Fire Brigades Union has been urged to call off the 24-hour strike planned for Thursday.

The call came amid indications that union leaders may be prepared to halt the strike if the armed forces begin military action this week.

John Prescott, the deputy prime minister, has refused to meet FBU leaders, saying it was up to them to call off the action.

Around 19,000 military personnel would be needed to provide emergency cover during the strike.

"The ball is in the FBU court," one Whitehall official said. "The union would be mad to strike on Thursday. It would lose all public support."

The Conservatives said that if FBU chief Andy Gilchrist refuses to halt the strike the government should take legal action to prevent it going ahead.

The shadow deputy prime minister said individual fire fighters did not want to be on strike when the country was at war.

David Davis stepped back from controversial comments by shadow defence minister Bernard Jenkin who said that the fire fighters were acting like friends of Saddam in threatening to strike during a national crisis.

"All the fire fighters I have met struck me as patriotic individuals. Therefore it is inconceivable that individual fire fighters would want to strike on Thursday if this country is at war - whatever their union leadership says," Davis said.

"I call upon Andy Gilchrist to call off his threat of strike action, and if he refuses, I call on the deputy prime minister to use the law to stop this strike occurring, at least until the hostilities are over.

"Irrespective of the effect on our troops, the firemen are our frontline response in the event of a major crisis or terrorist attack.

"This is particularly important in those areas where emergency preparation is not as advanced as it could be. It is therefore the fire fighters' duty, both to the armed forces and the public, to stay in their posts over the forthcoming weeks."

In a separate development, a poll for the fire service employers has found that public support for fire fighters is dwindling.

The survey, commissioned by the Local Government Association, found that 72 per cent of the public felt that fire fighters should accept the proposed pay increase of 16 per cent, together with reforms of working practices.

In the wake of a series of attacks on the FBU by politicians and members of the armed forces, 68 per cent of people said that fire fighters were wrong to plan further strikes at a time of national crisis.

The LGA claim the results of the survey vindicated their tough stance towards the FBU and demonstrated "the public's growing impatience".