The split between supporters and critics of America's tough stance on Iraq reached new levels of acrimony yesterday when France, Germany and Belgium vetoed a NATO move to offer military protection to Turkey.

The three countries said that security guarantees for Iraq's neighbour would reinforce "the logic of war".

President Bush said the move was "short sighted" and would damage the western security alliance.

Nicholas Burns, the US ambassador to NATO, added: "Because of their actions, NATO now is facing a crisis of credibility."

A new front in the transatlantic row was also opened up when France, Germany and Russia issued a joint statement calling for "everything possible" to be done to prevent war in Iraq.

They proposed that the UN weapons inspectors should be reinforced, and all three countries offered to provide additional resources to boost the hunt for Saddam Hussein's weapons of mass destruction.

But in a speech today, Jack Straw will dismiss that approach as ineffective.

"If Saddam bows to the UN's demands and cooperates promptly, what is the need for greater numbers of inspectors?" the foreign secretary will ask.

"If he maintains his refusal to cooperate, how will higher numbers help?"

The Guardian reports that the hardening attitudes in both camps will make it "near impossible" for Britain and the US to push for a second security council resolution authorising the use of force against Iraq.

Tony Blair could face severe difficulties ahead without the new mandate, the paper warns.

And the potential scale of his problems is revealed in a new opinion poll.

The Populus poll for today's Times finds that support for Labour has fallen to its lowest level for a decade.

Nearly nine out of 10 voters want the UN inspectors to be given more time while 57 per cent say the case for war has not been proven.