TONY Blair hinted at a U-turn on unpopular police force mergers yesterday as Cleveland lobbied MPs against a single force for the North-East.

The Prime Minister said forces might be allowed to work together more closely on cross-border crime, without formal amalgamation - a system called federation.

Mr Blair's comments suggested Cleveland might not be forced to merge with Durham and Northumbria, to create a force stretching from the North Yorkshire Moors to the Scottish border.

Cleveland is fighting the plan in favour of two "city region" forces, insisting a "super-force" would undermine local policing.

But the Tories immediately accused the Prime Minister of a split with Home Secretary Charles Clarke, who has ruled out a federation.

In contrast, Her Majesty's Inspectorate of Constabulary (HMIC) - which first proposed the mergers -warned that a federation would be a missed opportunity.

That suggests Mr Blair is desperately trying to move back from merging police forces as the backlash grows across large parts of the country.

To add to the confusion, Hazel Blears, the Police Minister, said yesterday that the North-East forces were likely to be the first to merge - with a decision as early as next month.

Ms Blears said: "There are some forces enthusiastic about merging in a voluntary way, such as in the North-East and Wales. They feel it's the right thing to do for their communities."

Mr Blair spoke as the leaders of police authorities from across Britain met local MPs at Westminster to highlight their opposition to the plans.

At Prime Minister's Questions, he said: "One possibility is that you have strategic coming together on certain issues, rather than mergers.

"It's got to be looked at on a case-by-case basis and we should listen to what people are saying."

Later, Mr Blair added: "There are a number of different directions that this could take and it could be different in different parts of the country."

Tory leader David Cameron leapt on the comments, saying Mr Clarke had insisted smaller forces must be abolished - with no exceptions.

He added: "The Prime Minister is saying they could survive if they share certain tasks strategically. Will he make sure the Home Secretary thinks again and doesn't force through amalgamations?"

Mr Clarke has said he will order "foot-dragging" forces to merge, although that would require a vote by MPs.

The Association of Police Authorities raised the stakes further by claiming the mergers - and a subsequent reordering of the Crown Prosecution Service - would cost £1bn.