Britain's Blair government would have liked to have gone down the diplomatic route to disarm Saddam Hussein but became a "prisoner" of a U.S. policy heading towards war, the former head of the United Nations weapons inspectors told the Chilcot Iraq inquiry on Tuesday.

Both Britain and the U.S. should have realized "their sources were poor" when his inspectors found nothing in Iraq, said Hans Blix. It should have set alarm bells ringing in London and Washington when the inspectors repeatedly failed to turn up any evidence that Saddam still had active WMD programs, he told the Chilcot inquiry.

Blix said it was his "firm view" that the invasion of Iraq was illegal, adding: "I think the vast majority of international lawyers feel that way." Lord Goldsmith, Tony Blair's attorney general, had "wriggled" before he finally provided the legal authority for British troops to invade, said Blix. "He was not quite sure it would have stood an international tribunal. Nevertheless, he gave the green light to it."

Directing his criticism at the U.S. rather than Britain, Blix told the inquiry: "The U.K. was wedded to the U.N. route but eventually became prisoner of the American train." He described the Bush administration of being "high on military" in the wake of the 9/11 attacks on the U.S. in 2001. "They felt that they could get away with it and therefore it was desirable," Blix told the inquiry.

Blix called claims by Condoleezza Rice, the then U.S. secretary of state, that Washington's policy was one of trying to uphold the authority of the U.N. security council as "totally absurd". He described the close relationship between previous U.N. weapons inspectors and U.S. and U.K. intelligence agencies as "scandalous". So, too, he said, were U.S. and U.K. intelligence claims, based on a forged document, that Iraq was trying to get its hands on uranium oxide for its alleged nuclear weapons program.

Blix said he had privately confided to Blair in the autumn of 2002 - before the inspectors returned to Iraq - that he thought it was "plausible" that Saddam did have WMD. However, in the weeks leading up to the 2003 invasion - after the inspectors had failed to uncover anything significant – he had cautioned Blair that there might not be  anything. Blix said he told Blair: "Wouldn't it be paradoxical if you were to invade Iraq with 250,000 men and find very little?" He added: "I gave a warning that things had changed and there might not be so much."

Blix said the inspectors had visited 30 sites based on tip-offs from British and U.S. intelligence but found little other than some old missile engines and a sheaf of nuclear documents.

The inquiry earlier revealed that defense ministers were formally warned that military commanders were pressing for better protection from improvised explosive devices, IEDs, than that provided by thinly-armored Snatch Land Rovers. Lt. Gen. Sir Nicholas Houghton, then chief of joint operations, wrote: "We need a medium-weight PPV (protected patrol vehicle) … in order to provide a significantly enhanced physical protection against EFP IEDs (explosively formed projectile improvised explosive devices) and RPGs (rocket-propelled grenades) in order to prosecute our missions successfully without unnecessary casualties," according to a declassified memo dated July 2006. A handwritten note on the memo reads: "NB Note ministers can no longer say in the house that they have had no request from commanders for an alternative to the Snatch."

The inquiry has heard how a shortage of helicopters in both Iraq and Afghanistan exacerbated the problem as troops had to rely more on vulnerable Snatch Land Rovers than they otherwise would have had to.

Lt. Gen. Sir Robert Fulton, deputy chief of defense staff responsible for equipment from 2003 to 2006, defended the military's response to growing concerns about the Snatch Land Rover. He told the inquiry that as much extra armor was added to the vehicle as possible, but eventually an alternative was needed.

"This was a constant process of adding more and more protection," he said. "Of course there is going to come a time when the enemy has gone on adding kilograms of explosive and you can't go on adding kilograms of steel, and therefore there has to be a step change."