FBU leader Andy Gilchrist, addressing a 5,000 strong rally in Glasgow, said it was time to be "less reasonable."

He was speaking as the latest 48-hour strike got under way at 0900 GMT on Saturday, with thousands of military personnel providing cover over the weekend.

As long as firefighters and their representatives are treated with contempt and we don't get the right to negotiate, there will be strikes Andy Gilchrist FBU leader

The meeting with Mr Prescott will be the first with the FBU since he announced last week he was planning to impose a pay settlement in a bid to end the dispute.

But Mr Gilchrist said: "We have suspended strikes, we have cancelled strikes, we have been reasonable.

"Well, perhaps the time to be a little less than reasonable is here.

"As long as firefighters and their representatives are treated with contempt and we don't get the right to negotiate, there will be strikes.

"That will be, without doubt, the decision taken by the Executive Council on Monday."

Mr Gilchrist said he would not accept a settlement of anything less than �30,000 a year, and pledged to rebuff any calls for job losses.

He described the strike as a classic "working class" struggle.

Fresh walkouts

The FBU's rallying call comes after Mr Prescott's threat to impose a deal.

The government is preparing to reactivate the Fire Services Act of 1947, repealed in 1959, which will allow the government to specify pay, terms and conditions.

Military personnel are providing cover

Before the talks with the government, Mr Gilchrist and senior union officials will also meet the contact group of union leaders set up by the TUC.

At the meeting officials are expected to press for fresh walkouts, as employers insist anything more than a 4% pay rise needs to be paid for by modernising the fire service.

The employers want strikes suspended before they will return to the table.

Councillor Ted George, chairman of the employers, wrote to Mr Gilchrist to stress that when no further strikes were timetabled, talks could resume at the conciliation service Acas.

Employers officials said there was no reason why negotiations could not resume on Tuesday, but only if the FBU decided to pull back from naming further strikes.

The first callout for the military came even before the latest strike started.

Troops were called to a blaze at Croydon in south London, which had been raging through the night. They took over from firefighters 10 minutes before the start of the strike.