One in five British Muslims has at least some sympathy with those who have travelled to Syria to fight with Islamic State, a poll reveals.

The Survation poll of British Muslims for The Sun newspaper found that support was even higher among younger Muslims, with nearly one in four 18 to 34 year olds feeling some sympathy.

Support was also high Greater Manchester, where one in 10 Muslims said they had a “lot of sympathy” with their coreligionists who join the terror group.

Responding to the poll, the Labour Party’s London mayoral candidate Sadiq Khan said: “It is clear that Britain needs to take its head out of the sand and act to tackle extremism and radicalisation at home.

“Tackling extremism is a challenge for everyone but I believe British Muslims have a special role to play.”

Meanwhile 38 per cent of UK Muslims blame ISIS terror attacks on “Western foreign policy, such as the invasion of Iraq”, while the same number think Muslims should not have to condemn terrorist acts carried out in the name of Islam.

Omar Elhamdoon of the Muslim Association of Britain told The Sun: “When we do condemn the acts it is maybe indirectly saying we are taking responsibility, and owning the problem when it is nothing to do with us. They are not representing Islam.”

Back in February another poll found that third of Muslims in Britain sympathise with the Charlie Hebdo killers. A total of 27 per cent said they have “some sympathy” for the killers who murdered 12 in an attack on the magazine’s offices in Paris.

One in five respondents in that poll also said the Islam was not compatible with Western society, while one in four disagreed that attacks on those who publish cartoons of Mohammed “can never be justified”.

According to the 2011 census, around 2.7 million Muslims live in Britain, and if the most recent poll is representative, that means some 500,000 would have at least some sympathy for the jihadis.

Mr Elhamdoon said: “There are people who see what happens from Britain in other countries and they will be angered. Some of those then have a tendency to be radicalised.

“This could be radicalised by them going out to do something or just by having those feelings.”