Festival-goers at a nationalist, right-wing concert in Germany were taken by surprise when souvenir T-shirts they were given had a secret anti-far right message that emerged only after being washed.

The slogan on the shirts first read "hardcore rebels" along with a skull and nationalist flags. But once washed the slogan turned into a message from a group offering help to right-wing extremists to break away from the neo-Nazi scene.

"If your T-shirt can do it, you can do it too - we'll help you get away from right-wing extremism," read the slogan on the shirts after their first wash.

The anti-far right shirts were handed to 250 people at a Rock for Germany concert in Gera by organisers after they had been donated anonymously.

They were provided by EXIT, a group which helps people disassociate themselves from the far-right.

Festival organiser Gordon Richter of the far-right NPD party said the stunt was a waste of money.

"It's kind of pathetic that anyone spent money for something like that," Mr Richter said.

But he said many who got the Trojan horse shirts thought it was a creative idea.

Bernd Wagner, founder of EXIT, said the T-shirts were designed to reach their main target group: right-wing extremists contemplating getting away.

"We wanted to raise awareness about our program, especially among the young and less committed," Mr Wagner said.

Reuters