Greece's finance minister insists film footage purportedly showing him giving Germany the middle finger is a fake.

Yanis Varoufakis claims the video had been doctored after being shown the clip on a late-night German political talk show on which he had been invited to discuss his country's financial crisis and relations with Berlin.

In the film, taken in Croatia in 2013, Mr Varoufakis is apparently seen making the rude gesture as he is heard to say: "Greece should simply announce that it is defaulting...and stick the finger to Germany."

But denying the claim, the former economics professor told the German TV host Guenther Jauch: "That video was doctored. I never gave the finger."

Mr Jauch's production company has said it is checking the video but so far had found no evidence it had been tampered with.

The footage is set to further heighten tensions between Athens and Berlin over Greece's €240bn bailout.

Mr Varoufakis has already been warned time is running out and told he must put forward concrete proposals if the country wants to secure funds agreed under an extension to its rescue package.

Athens got a lifeline last month when ministers agreed a four-month deal on extending its current EU-IMF bailout, subject to reforms being agreed.

The new radical left-wing government has pledged to streamline bureaucracy and tackle smuggling but its blueprint has been criticised as lacking detail.

The next payout of €7.5bn is due at the end of April.

Greece may have to leave the currency union if no reform programme can be agreed.