In addition to Leopard 2 tanks, German armaments company Rheinmetall wants to buy 96 Leopard 1 tanks from Swiss defence firm Ruag to send to Ukraine, the Swiss newspaper Tages- Anzeiger reported on Saturday.
The deal involves used and non-operational Leopard 1 tanks, which Ruag bought in 2016 in Italy and which are still there.
"Rheinmetall wanted to buy the vehicles and made it clear that they would be delivered to Ukraine after being reconditioned," a spokesperson for Ruag told Tages-Anzeiger.
Ruag requested a non-binding preliminary clarification from the State Secretariat for Economic Affairs, and received a negative answer, according to Tages-Anzeiger.
The deal could however still go through and is likely to be discussed by Switzerland's Federal Council. When exactly, is unclear.
There was no immediate response to requests for comment from Ruag or Rheinmetall.
The predecessor to the Leopard 2, Leopard 1 tanks are lighter, with a smaller engine and a shorter firing range than their more modern counterpart, but are said to be able to hold up against Russian T-72 tanks.
The Swiss and German governments said on Friday that Germany had asked Switzerland to sell back some of its mothballed Leopard 2 tanks, in a deal that could allow Western countries to increase military aid to Ukraine.
In a letter seen by Reuters, the German government said it would be very grateful if Switzerland could approve the purchase of mothballed Leopard 2 tanks by Rheinmetall, as it had done in the past, if those tanks were not intended to be put into operation again.
"The tanks will not be sold onto Ukraine. We guarantee that they will remain in Germany or with our partners in NATO and the EU, to plug gaps that have emerged through the transfer of Leopard 2 tanks (to Ukraine) and to improve the supply with spare parts in general," the letter said.
Under its neutrality laws and a separate arms embargo, Switzerland is prohibited from sending weapons directly to Ukraine.
(Reporting by Noele Illien, editing by Giles Elgood)