"At best, it is the start of a process that could lead to direct talks between Ukraine and Russia," Scholz said in an interview with the German weekly Stern.

The June summit would discuss "the safety of nuclear power plants, grain exports, prisoner exchanges" and the risk of a nuclear escalation, Scholz said.

But the chancellor warned that "nobody should have excessive expectations", adding: "We are not negotiating the end of the war".

He likened the talks to a "delicate little flower".

Switzerland has invited more than 160 delegations to the peace conference, although Russia is not currently on the list.

Russia, which launched its full-scale invasion of neighbouring Ukraine in February 2022, has dismissed the Lucerne event as a US-orchestrated plot.

Moscow has repeatedly said it will not participate in any talks unless Kyiv accepts Russia's annexation of the roughly 20 percent of Ukraine's territory it currently occupies.

The attendance of Ukrainian President Volodymyr Zelensky and US President Joe Biden has not been confirmed.

Another big unknown is whether Moscow's key ally China will attend.

"We are trying to ensure that countries that are not wholehearted supporters of Ukraine also take part. Brazil, South Africa or China for example," Scholz said in the interview.

Meanwhile, Russian President Vladimir "Putin continues his merciless campaign against Ukraine unabated", Scholz said.

Russian troops last week launched a surprise new ground offensive in the Kharkiv region, which has forced thousands to evacuate and pushed Kyiv to mobilise reinforcements.

Ukraine would "need our support for a long time", Scholz said.

sea/hmn/ach

STERN GROEP