TONY BLAIR was last night bolstered by a scathing US report blaming intelligence failings, not political pressure, for errors over Iraq.

The future of the CIA was called into question by the devastating conclusions of the Senate Intelligence Committee.

Intelligence on Saddam Hussein's weapons of mass destruction (WMD) was flawed or overstated, the report concluded.

And British secret services were implicated in the "global intelligence failure".

But there was no evidence of political pressure from President George Bush's administration or, by implication, allies in No 10.

That will be seized on by the Prime Minister's allies as he prepares for the findings of a similar British inquiry.

Mr Blair has already conceded that Iraqi WMD may well never be found, ahead of Lord Butler's report next week.

But Sir Menzies Campbell, Liberal Democrat foreign affairs spokesman, said a second US probe would deal more thoroughly with the issue of political interference.

The Butler inquiry, which the Lib Dems and Tories have boycotted, did not have the remit to probe politicians' actions, Sir Menzies told BBC Radio 4's PM programme.

"It may be that we will never get a definitive view here in the United Kingdom about the extent to which the judgement and actions of politicians may have contributed to what everyone now accepts is going to war on a false prospectus," he said.

"From the point of view of the public, it is yet another indication that the case for going to war against Saddam Hussein, the case that only military action would do against him, is being further and further undermined."

Mr Blair could be damaged if suggestions that Lord Butler criticises the omission of caveats from his dossier following No 10 interference prove correct.

US intelligence analysts fell victim to "group think" assumptions that Iraq had WMD, senators concluded.

The report goes on to say that US intelligence failures run so deep that money alone cannot put them right.

Senator Pat Roberts, a Kansas Republican who heads the committee, said assessments that Iraq had chemical and biological weapons and could make a nuclear weapon by the end of the decade were wrong.

"As the report will show, they were also unreasonable and largely unsupported by the available intelligence," he said.

"This was a global intelligence failure."

The report repeatedly criticises departing CIA director George Tenet, accusing him of skewing advice to top policy-makers with the CIA's view and elbowing out dissenting views.

It blames him for not reviewing President Bush's 2003 State of the Union address, which contained now-discredited references to Iraq's attempts to purchase uranium in Africa.

Mr Tenet has resigned and leaves office tomorrow.

White House spokesman Scott McClellan said the committee's report essentially "agrees with what we have said".

Downing Street and the Foreign Office declined to comment on the senate committee findings ahead of the Butler report.