Switzerland is seeking talks with the United States, the government said on Wednesday, after Washington tried to raise the price for new fighter jets the neutral country is buying to upgrade its air defences.

Switzerland and the United States are at odds over the price of 36 US-made F-35 fighter jets, with Washington now seeking a significantly higher payment than originally expected. The Swiss government maintains the aircraft were purchased at a fixed price of some 6 billion Swiss francs ($7.

Switzerland and the US are at odds on the agreed price for three dozen F-35A fighter jets the country wants to buy from Lockheed Martin Corp., adding to existing tensions over US tariffs.