"There is no reason to reply favourably to the German request to transmit Swiss military equipment to Ukraine," Economic Affairs Minister Guy Parmelin explained in a letter to German Defence Minister Christine Lambrecht.

Berlin wants to send Ukraine 12,400 pieces of Swiss-made ammunition to be used by German Gepard self-propelled anti-aircraft guns that Kyiv has requested to shoot down cruise missiles and drones used by Russian invasion forces.

"The equality of treatment deriving from the law of neutrality does not allow Switzerland to approve a request to send military equipment of Swiss origin to Ukraine while this country is involved in an international armed conflict," Parmelin said.

On Wednesday, Switzerland agreed to provide $100 million in aid to Ukraine to help provide drinking water and rehabilitate damaged energy infrastructure as winter approaches.

Despite being neutral, Switzerland has also adopted all the sanctions already imposed by the European Union on Russia over its invasion of Ukraine in late February, including against President Vladimir Putin.

Some Swiss politicians thought this was already a step too far, but President Ignazio Cassis has repeatedly defended the decision.