The London–based Muslim cleric Abu Hamza al-Masri said the hijackers involved in attacks on Washington and New York should be hailed as "martyrs" if it emerges they were carried out in the name of Islam.
Mr Hamza, the imam of the north Finsbury mosque who was accused of masterminding a bombing campaign in Yemen two years ago, refused to condemn the terrorist attacks and said they may have been carried out in "self-defence".
His comments were attacked as "totally unrepresentative" by other British-based Muslim groups.
Mr Hamza said: "I won't condone what has happened and I won't condemn it because I don't know who has done it yet. If somebody has done this just for earthly gain and political advancement then obviously it is a cheap cause.
"But if it was done because people are desperate and their lives have been threatened, then that is a respectable cause ... Then those people who carried out the attacks would be martyrs. Martyrdom is the highest form of jihad [holy war].
"If you do things for the cause of God, losing your life for it is the highest form of belief. This is in the Koran. America thinks it comes first, but Muslims believe a believer comes first."
He added: "When you damage a people, and they have no home and no hope, and their babies and children are killed, then they retaliate. America took decisions to give arms to certain people and take arms away from others. What happened yesterday would be self-defence."
The Egyptian-born Mr Hamza, who lives in west London, said he sympathised with the victims of the tragedy but also had some sympathy for Osama bin Laden, who is suspected of involvement in the attacks. Mr Bin Laden has been the victim of an American "witch hunt" but was unlikely to have ordered the attacks himself, Mr Hamza said.
"He has been under a very tight pressure cooker but I don't think he is capable of doing a thing like this. But he has probably got millions of sympathisers," he said.
Mr Hamza, who is half-blind and has a claw hand after he was wounded in fighting in Afghanistan, is the leader of the Supporters of Sharia Muslim group and came to prominence in 1999 when five Britons of Pakistani origin were convicted in Yemen.
They were sentenced to between three and seven years for plotting to blow up targets in the capital, Aden, including the British consulate, a church and a hotel. Mr Hamza's teenage son and stepson were among those convicted and prosecutors said he sent the group to Yemen.
Mr Hamza denied this and the five insisted they had been tortured into signing confessions. They were also accused of working with Islamic radicals who kidnapped 16 Westerners in December 1998. Four of them died in a shoot-out during a botched rescue attempt by Yemeni security forces.
Other Muslim groups condemned Mr Hamza and said his views were unrepresentative of the Muslim community.
Dr Ghayasuddin Siddiqui, the leader of the Muslim Parliament of Great Britain, said: "We have nothing to do with him or his views. I don't think he has any support within the Muslim community. He speaks for himself and maybe just a handful of followers.
"The Muslim community are still in a state of shock having seen what has happened on television. We urge people to keep their cool and remain calm. We want to find out who the culprits are and they should be punished.
"Islam does not support what has happened in any shape or form. The Muslim community worldwide cannot find any justification for it and does not approve of it."
The Muslim Council of Britain also distanced themselves from Mr Hamza's comments and called the attacks "senseless and evil".Reuse content