What is the basic sticking point?

Unsurprisingly, money.

An outline proposal hammered out late last week between fire service managers and workers would have boosted firefighters' pay by 16% over two years - taking their salaries to approximately �25,000.

While the increase was well below the 40% rise the firefighters had originally demanded (a salary of �30,000) the government reaction was dismissive.

Chancellor Gordon Brown on Sunday rejected the 16% increase as unaffordable.

And Tony Blair rammed the message home on Monday, warning that an award on that scale could trigger copycat demands from other public sector workers, putting economic stability at risk.

The Fire Brigades Union is still holding out for a what its leader Andy Gilchrist terms a "significant" offer on pay.

Mr Gilchrist has also called on the government to speak with one voice on the dispute.

Prior to Mr Brown's intervention, Deputy Prime Minister John Prescott had suggested that a 16% pay rise over three rather than two years might be possible.

How much would a 16% pay increase cost the public purse?

Opinion is sharply divided.

The government says upping firefighters' pay by 16% would cost �450m.

But it has warned that the final bill would rise to �4bn if the settlement were extended to all local authority workers, and to a whopping �16bn - equivalent to a 30% increase in income tax - if the same deal were offered to the rest of the public sector.

The Fire Brigades Union, on the other hand, believes that a 16% pay rise for its members would cost just �200m - less than half the government's estimate.

The FBU's Andy Gilchrist says this was the figure supplied by fire service managers when the 16% pay deal was originally discussed last week.

Other union members have accused the government of exaggerating the knock-on effects of an increase in firefighters' pay.

They argue that since a high proportion of public sector workers have recently agreed more moderate pay rises, the scope for copycat demands is actually fairly limited.

Where do we go from here?

It seems likely that fresh pay proposals will be needed to get both sides back around the negotiating table.

But when talks resume, it is clear that the Fire Brigades Union will come under intense pressure to accept reforms to firefighters' working practices as part of any final deal.

Tony Blair said on Monday that any pay rise over and above the original offer of 4% will have to be paid for by efficiency gains achieved by streamlining the way the fire service works.

Possible reforms include an end to the FBU's current ban on overtime, and the introduction of more flexible shift patterns.

The firefighters, however, are deeply suspicious of the government's reformist agenda. Many believe that the proposed changes are a smokescreen for budget cutbacks and possible job losses.