Switzerland remains opposed to exporting arms to war-torn Ukraine, the famously neutral country's President Alain Berset said Tuesday on the sidelines of meetings at the United Nations.

Switzerland bars re-export of Swiss weaponry to nations at war, but the issue of the country's long tradition of neutrality has been under debate since Russia's full-scale invasion of Ukraine just over a year ago.

"The discussion about the export of arms, weapons... while we have (our) legal framework in Switzerland, it is not possible to do it," Berset, who currently holds the country's rotating one-year presidency, told reporters on the margins of UN meetings on women's rights.

"For the government and for the Federal Council, we have to, and we want to, maintain this legal framework and to work in this legal framework," he said.

His comments came after Berlin requested in late February that German arms manufacturer Rheinmetall be permitted to acquire old Swiss Leopard tanks, guaranteeing they will not be transferred to Ukraine.

While the wealthy Alpine country, which is not a member of the European Union, has followed the bloc's lead on sanctions targeting Moscow, it has so far shown less flexibility on its military neutrality.

"These sanctions, they are absolutely compatible with the neutrality," said Berset, speaking in English.

Despite pressure from Kyiv and its allies, Switzerland has so far refused to allow countries that hold Swiss-made weaponry to re-export it to war-ravaged Ukraine, and has to date rejected explicit requests from Germany, Spain and Denmark.

Several initiatives are under way in parliament towards relaxing the re-export rules, but any decision is likely months away.

Berset, who met in New York with UN chief Antonio Guterres just before the Secretary-General traveled to Ukraine, noted that the Swiss parliament "has a lot of possibilities to change the laws."

"If the parliament would agree to change this legal framework, then we will work in the context of this new legal framework, but we will also take time," he said.

But, he emphasized, "It's not possible to make exception to the legal framework."