Germany's domestic intelligence chief has warned that the country's far-right 'identitarian' youth movement is becoming increasingly radicalised.

"There are several indications of contacts and intertwining of the 'identitarians' with far-right people or groups, so that we are working on the assumption that there is a far-right influence," Hans-Georg Maassen, head of the Bundesverfassungsschutz (BfV), told the Funke Media Group newspapers on Sunday.

The "increasing radicalization," he added, was likely to take the form of spontaneous, provocative actions aimed at political parties, mosques, and Islamic cultural centres, or homes for asylum seekers.

The identitarian movement arose as a youth movement in France, and has spread across Europe. Followers claim they are not racist, but are defending the identity of white culture against immigrants and liberal elites.

Critics argue that they advocate white supremacism, and are attempting to detoxify far-right ideology.

Identitarian activists have staged high profile stunts, such as an incident in August 2016, in which members of the movement scaled the Reichstag edifice in Berlin and hung banners with the anti-immigrant slogan 'Secure borders, save lives'. In France, activists have set up stalls distributing products containing pork in predominantly Muslim neighbourhoods.

German intelligence has placed the movement under surveillance.

In recent months, an alliance has been forged between key members of the European identitarian movement and the US alt-right, a white nationalist movement which loudly backed Donald Trump during the US presidential campaign. IBTimes UK has reported on attempts to spread the movement to the UK.

Daniel Fiss, a spokesman for the movement dismissed Maassen's accusations as "completely without substance" in a Facebook statement.

Speaking to Deutsche Welle, he rejected claims the movement is affiliated with the far-right.

"Of course we see ourselves as a patriotic homeland-bound youth, but we show a clear separation from far-right extremism," he said.

The movement has previously been accused of ties with far-right groups, with the German Interior Ministry alleging in 2015 that identitarians had links with the neo-Nazi NPD and anti-refugee vigilante groups.

There was a spike in support for the anti-immigrant AfD party and the Pegida movement after the 2015 refugee crisis, which saw millions of refugees granted asylum in Germany by the government of Chancellor Angela Merkel.