Almost two thirds believe Blair is "losing his grip," according to the Mori poll for the Financial Times.

A total of 28 per cent said they had never trusted him, while 38 per cent said they have not trusted him since the start of the year.

Elsewhere, 30 per cent said they "strongly agree" that Blair is losing his grip while 33 per cent tend to agree.

Only 31 per cent said they were satisfied with Blair's performance as prime minister, against 61 per cent who were not.

Mori interviewed 1,002 adults by telephone between June 20 and 22.

Blair has come under fierce criticism in recent weeks over his handling of the Iraq war.

A poll last month showed that the majority of British voters believe Britain and the United States deliberately exaggerated evidence that Iraq had weapons of mass destruction (WMD) in order to win support for going to war.

A parliamentary foreign affairs committee is currently investigating claims that Britain embellished intelligence on Iraq's WMD.

A Washington report adds: Deadly attacks on coalition troops and the slow progress of reconstruction efforts in Iraq are eroding support for the US-led occupation.

Only 56 per cent of respondents in the USA Today/CNN/Gallup poll released Monday said Iraq was worth going to war, down from 73 per cent in April.

The percentages of people expressing confidence US forces would find evidence of Iraq's banned weapons or ousted Iraqi leader Saddam Hussein also slipped by large margins.

Some 55 per cent said they were confident US-led forces would find weapons of mass destruction, down sharply from 84 per cent in late March, when the war was still raging.

Fewer than half those polled, 48 per cent, said they were confident Saddam will be captured or killed, down from 70 per cent in March.

The poll of 1,003 adults taken Friday through Sunday has a margin of error of three percentage points.