A man has turned himself in and another has been arrested for a heist on a high-stakes German poker tournament that netted thieves nearly a quarter of a million euros, authorities say.

A 21-year-old German, escorted by his lawyer, presented himself at the prosecutor's office in Berlin on Monday and confessed to taking part in the heist, Sjors Kamstra, a spokesman for prosecutors, told a news conference on Wednesday.

The man had 'an immigrant background' and 'after intensive questioning, named his accomplices,' he said.

He had also offered to return his share of the €242,000 police said, although the money was currently stashed 'with a third party'.

The other gang members were a 19-year-old German, a 20-year-old from Turkey and another 20-year-old of unknown nationality, Kamstra said.

Later on Wednesday a second suspect, aged 20, was arrested 'without resistance' after presenting himself to routine security officers in a metro station in the city, police said, without giving his nationality.