About 40 neo-Nazis were put under investigation by police in Britain amid fears that they are plotting terrorist attacks against Muslims around the country, the Sunday Times reported. The neo-Nazi group reportedly operates in far-right hotspots where they are planning atrocities, predominantly in Yorkshire, Leeds, Dewsbury and Batley, police intelligence sources reported.

As young neo-Nazis have become a growing threat in the U.K., a neo-Nazi group called National Action, which glorifies acts of violence and terrorism, was labeled a terrorist organization and banned for the first time last year.

National Action had earlier glorified the killing of Jo Cox, the British Labour Party member of parliament, by white supremacist Thomas Mair, as the court described Cox's murder as a terrorism offence. The Southern Poverty Law Center (SPLC), a civil rights group based in the U.S. state of Alabama, said on its website that it had obtained records showing Mair had links to the National Alliance dating back to 1999. He also had letters printed in a South African pro-apartheid magazine, the SPLC said. An analysis of his internet usage on computers in local libraries also showed Mair's obsession with the far right. In the days and months before the attack, he read articles about Nazi figures, the Ku Klux Klan and Dylann Roof, the man convicted of killing nine black parishioners at a church in Charleston, South Carolina. He had also looked up the Wikipedia entry for Ian Gow, the last British lawmaker to have been killed before Cox, in 1990, reports said.

The murder, a week before Britain's referendum on European Union membership, shocked the country. Cox was the first British lawmaker killed in office in a quarter century. Cox had been a prominent voice arguing for Britain to remain in the EU during a divisive and often angry referendum campaign that focused heavily on the issue of immigration. She had also urged Britain to take in more refugees fleeing the violence in Syria.

The killing of Cox by a white nationalist terrorist indicates growing violent white supremacy trends, violence from far-right extremism and neo-Nazi groups across the country.

As the number of white Britons arrested on terrorism-related offences increases, Muslims in the U.K. have been suffering from rising hate crimes in the country. Anti-Muslim hate crimes have skyrocketed by more than 500 percent following the May 22 concert suicide bombing in Manchester, local police said. Anti-Muslim hate crimes were already on the rise – by 186 percent – in April before the Manchester attack, which left 22 dead and dozens injured. This surge was prompted by the major terror attacks in Manchester and London, a senior police chief said.