Three men and two women were dragged from the public gallery of the lower chamber of parliament, the House of Commons, on Wednesday during a debate on a report published last week about pre-war intelligence on Iraq's alleged weapons arsenal.
Blair was interrupted by protestors screaming "murderer", "whitewash" and "no more war!" as he defended himself over the report by judge Lord Brian Hutton.
"I somehow feel I am not being entirely persuasive in certain quarters," Blair said to laughter shortly before proceedings were halted for the public gallery to be cleared.
Hutton's report, which cleared the government of a charge that it exaggerated Iraq's alleged weapons of mass destruction so as to justify the war, has been dismissed by some critics as a "whitewash".
Antiwar protesters have called
repeatedly for Blair to resign
Separately, five protesters dressed as judges were arrested on Wednesday after they threw white paint at gates barring the entrance to Downing Street, the central London street containing the prime minister's residence.
The paint-throwers said they were protesting against Blair's appointment of Lord Robin Butler to chair a new review of intelligence on Iraq's weapons.
Some critics say Butler is too much of an establishment figure to lead an independent inquiry.
Blair faces severe political pressure over allegations that his reason for backing the US-led war to unseat Saddam Hussein - that Iraq possessed weapons of mass destruction - had turned out to be false.
Former British weapons expert Brian Jones has alleged the government overruled intelligence analysts to present a "misleading" pre-war dossier on Iraq's banned weapons.
Blair told parliament that Jones' concerns were heard by his superiors and were not taken up and he defended the conclusions of Lord Hutton.
Jones' remarks poured fuel on the row over the justification given for war, frustrating Blair's attempts to draw a line under one of the most gruelling periods of his premiership.
'Great British blunder'
Blair was also attacked on Wednesday by former British foreign secretary Robin Cook.
Former minister Robin Cook says
the war damaged UK interests
Cook wrote in the Independent daily that the war in Iraq was the "greatest blunder" in British foreign policy since the 1956 Anglo-French expedition in Suez, Egypt.
"The war has neither disarmed a single weapon of mass destruction nor diminished the terrorist threat to British interests."
"It has, though, undermined the authority of the UN, divided us from our major partners in Europe and damaged our status in the Third World, especially Muslim countries," added Cook.
"The truth is that Tony Blair did not take Britain into Iraq because of any evidence of weapons of mass destruction. He joined in the war because he wanted to prove to President (George) Bush that Tony Blair was his best friend and Britain was his most reliable ally."
Butler inquiry doubts
Cook, who has been sniping at Blair since he left government, also dismissed the forthcoming Butler inquiry on the use of intelligence as a "diversion".
Some experts say the Butler intelligence review is likely to steer clear of the key question of whether politicians misused inelligence data.
Deciding whether military intelligence had been interpreted in good faith was a "very, very murky" area, warned David Baker, politics lecturer at Warwick university.
"I would have thought that they were trying to steer clear of the question, but they may be able to argue that they are trying to steer clear of it because it is unanswerable," Baker said.