Germany will authorise the delivery of tanks to Ukraine, Defence Minister Christine Lambrecht said Tuesday, in what would be a clear switch in Berlin's cautious policy on military backing for Kyiv.

The government has agreed to sign off the delivery of used Gepard anti-aircraft tanks, Lambrecht told an international meeting of defence ministers at the US Ramstein airbase, according to a copy of her speech seen by AFP.

Forty countries are holding emergency talks at the airbase in southwestern Germany on bolstering the defence capabilities of Ukraine.

The meeting, held at the invitation of the United States, is "focused on doing things to generate additional capability and capacity for the Ukrainian forces", according to US Defense Secretary Lloyd Austin.

France is delivering Caesar cannons with a range of 40 kilometres (25 miles) and Britain has provided Starstreak anti-air missiles and tanks.

The Gepard tanks will not come from the German army but from stocks held by the Krauss-Maffei Wegmann (KMW) arms group, government sources told AFP.

They were taken out of service 10 years ago and need to be technically upgraded, the sources said.

German Chancellor Olaf Scholz has come under fire for refusing to directly send heavy weapons to Ukraine, despite announcing a "turning point" in German defence policy in response to the war.

Critics have accused Scholz of weak leadership and say his Social Democrats (SPD) are too reluctant to break from their historic policy of detente towards Moscow.

Scholz has even faced criticism from within his own coalition government, a partnership between the SPD, the Greens and the liberal FDP.

The chancellor has justified his cautious approach by saying he wishes to avoid a direct confrontation between NATO and Russia, a nuclear power. 

But according to a draft document seen by AFP on Tuesday, the three coalition parties now plan to present a joint proposal in parliament calling for the delivery of heavy weapons to Ukraine.

The document calls on the government to "continue and, where possible, accelerate the delivery of necessary equipment to Ukraine, including extending the delivery of heavy weapons and complex systems".

It also suggests that Ukrainian soldiers should be trained in Germany and other NATO countries to operate the weaponry.