Extremism by Islamic State terrorists overseas is causing a fierce reaction by the UK far right, a senior Home Office adviser has warned.

The adviser, who has 27 years of experience dealing with right-wing extremists told the BBC that the government had underestimated the threat they pose to Britain.

He said that since last year, five splinter groups have been formed from existing organisations, following a more extreme and violent ideology.

The adviser, who prefers to remain anonymous, said that one group member told him he would like to see death camps for all ethnic minorities in Britain.

“When I asked who he would like to put in the death camps, he just listed everyone that he didn't see as white British,” he said.

According to Tell Mama UK, an organisation which monitors anti-Muslim hate crimes, the actions of the IS terror group in the Middle East has caused an upsurge in Islamophobia.

In August it received 219 reports of anti-Islamic incidents, which was the same month as the beheading of the American journalist James Foley by an IS terrorist who appeared to speak with a British accent.

In the same month, the CST tallied up 150 antisemitic incidents, the third highest monthly total since records began, while in July, 302 incidents were recorded - a five-fold increase compared with July 2013.