British prime minister Tony Blair has provoked unionist fury by comparing Islamist extremists with Protestant killers in the North.
Mr Blair was accused of character assassination after making the reference during a speech on global terrorism and religious intolerance.
In an impassioned defence of his foreign policy, he insisted Britain's involvement in Iraq and Afghanistan was a clash about civilisation rather than between civilisations.
Tony Blair
Mr Blair also said ministers have been advised against using the phrase Islamist extremist.
He told the Foreign Policy Centre in London last night: "There are those
- perfectly decent-minded people
- who say the extremists who commit these acts of terrorism are not true Muslims. And of course, they are right.
"They are no more proper Muslims than the Protestant bigot who murders a Catholic in Northern Ireland is a proper Christian.
"But unfortunately he is still a Protestant bigot. To say his religion is irrelevant is both completely to misunderstand his motive and to refuse to face up to the strain of extremism within his religion that has given rise to it."
The comparison outraged Ian Paisley Jr, a Democratic Unionist member of the Northern Ireland Assembly. He said today: "This is a studied insult of the Protestant community."
Mr Paisley claimed Mr Blair had ignored decades of republican violence as he focused on one side of Northern Ireland's religious divide.
"The Prime Minister's comments singling out Protestantism as a root cause of terrorism is so unbalanced that it not only reveals the true nature of the Prime Minister but also identifies a weakness in his judgments, his character and his understanding," he said.
"He has singularly failed to point the finger at the IRA, and the Roman Catholic Church that refused to condemn years of IRA terrorism.
"Why is the Prime Minister so biased when it comes to understanding Northern Ireland? Why does he feel it necessary to attack the character and identity of the majority of citizens who are loyal and indeed victims of IRA terrorists?
"This deliberate character assassination of the Protestant community is a disgraceful, ill-thought-out and indeed provocative attack on a community that does not deserve to be labelled in the false and unacceptable manner that he has done.
"The PM has revealed that he is nothing more than a charlatan and liar and cannot be regarded as a person who can even begin to understand the situation in Northern Ireland."
Relatives for Justice, which represents families in Northern Ireland whose loved ones were victims of alleged collusion between loyalists and the British security forces, accused unionists of revisionism and denial about Protestant paramilitary violence.
"Comments by Tony Blair last night likening a 'Protestant bigot' who killed Catholics to 'Islamic extremists' has drawn a predictable knee-jerk reaction from some unionists who prefer to deny the extent of loyalist violence which emanated from within their own communities," Mark Thompson said.
"These same commentators want to ignore and deny that this violence was sectarian and want to present a revisionist view of the conflict where the only actors were republican.
"Their continued silence on ongoing loyalist violence and loyalist racism stands in stark contrast to their swift condemnation of Mr Blair's comments last night and today."
Mr Thompson said the focus today should have been on Mr Blair's failure to mention the role of British intelligence in recruiting, arming and controlling loyalist paramilitaries.