A Dutch MP who described the Koran as a "fascist book" has been banned from entering the UK amid fears his presence would endanger public security.
Freedom Party MP Geert Wilders was invited to show his controversial film - which links the Islamic holy book to terrorism - in the UK's House of Lords.
But Mr Wilders, who faces trial in his own country for inciting hatred, has been denied entry by the Home Office.
Mr Wilders said the move was "cowardly" but one peer said it was "welcome".
Mr Wilders' film Fitna caused outrage across the Muslim world when it was posted on the internet last year.
Its opening scenes show a copy of the Koran followed by footage of the 9/11 attacks in the US and the bombings in Madrid in 2004 and London in 2005.
The Dutch prime minister has said the film served "no purpose other than to offend".
Mr Wilders was asked to show the film at the House of Lords by UK Independence Party peer Lord Pearson.
However, he received a letter from the British Embassy in the Netherlands telling him he would not be allowed into the UK.
The Home Office said there was a blanket ban on Mr Wilders entering the UK under EU laws enabling member states to exclude someone whose presence could threaten public security.
"The government opposes extremism in all forms," it said in a statement, adding that it had tightened up rules on excluding those engaging in "unacceptable behaviour" in October.
"It will stop those who want to spread extremism, hatred, and violent messages in our communities from coming to our country."
Mr Wilders described the decision as "cowardly" and said he still intends to travel to the UK on Thursday to take part in the event.
He told the BBC: "It's incredible that an elected politician who was invited by one of your parliamentarians to a discussion with people who are against me, or in favour of me [was banned from the UK]."
Mr Wilders added: "I was surprised and very saddened that the freedom of speech that was a very strong point of UK society has been harassed. I thought Great Britain had the mother of all parliaments."
The Dutch government is reported to be trying to overturn the ban.
In the past, Mr Wilders has called for the Koran to be banned and compared it to Mein Kampf.
Earlier this year, a Dutch court ordered prosecutors to put Mr Wilders on trial for inciting hatred and discrimination by making anti-Islamic statements.
Labour peer Lord Ahmed, who expressed his concerns to the Parliamentary authorities about Mr Wilders' visit, said he welcomed the decision to ban the MP.
"It would be unwise to have him in the UK because this man's presence would cause hatred," he said.
"He has a case against him in the Amsterdam court for inciting hatred."
Lord Ahmed, who said other Muslim peers shared his concerns, stressed that Mr Wilders' views would certainly present a threat to public order.
"When Muslims are attacked obviously you will see people react to that."
But Lord Pearson said the decision to bar him was "weak and unacceptable in the extreme".
"The Home Office is guilty of appeasement on this, clearly."
The peer said the screening would still go ahead on Thursday whether Mr Wilders was present or not.
He said the parliamentary authorities were happy for the event to take place but had ordered extra security for it.
"The film does not threaten anyone," he said, adding that it simply showed how violent extremists justified their actions.
He said the screening would be followed by a debate on issues relating to the Koran, extremism and freedom of speech.