The US defence department informed Bern this week "that it will reprioritise the delivery of Patriot systems to support Ukraine, focusing on ground-based air defence" there, the Swiss defence ministry (DDPS) said in a statement.

"This also affects Switzerland, which will receive its production batches later than planned," it said.

US President Donald Trump on Monday announced a deal with NATO chief Mark Rutte for European NATO states to buy US weaponry -- particularly advanced Patriot systems -- and give it to Kyiv.

The move marked a pivot for Trump as his patience has worn thin with Russia's President Vladimir Putin for frustrating efforts to halt the war in Ukraine.

European countries -- including Germany, Norway, the Netherlands, Denmark and Sweden -- have expressed willingness to buy the weaponry for Kyiv.

The Swiss government statement said that the US decision to "reprioritise the delivery of Patriot ground-based air defence systems" to ensure they get to Ukraine would impact a Swiss order made three years ago.

Switzerland, which is not in NATO, had ordered five Patriot systems in 2022, with delivery scheduled to begin next year and to be completed in 2028.

With its traditional position of well-armed military neutrality, Switzerland would not pass on weapons systems to Ukraine.

But it said that "on July 16, the US Department of Defense informed the DDPS that Switzerland would also be affected by the new prioritisation and that deliveries intended for Switzerland would be delayed".

"It is currently unclear how many systems will be affected and whether the delivery of guided missiles will also be affected," it said.

"No statement can be made at this stage regarding the exact timing and any further implications for Switzerland," the statement added, stressing that "clarifications are ongoing".

Washington had already informed Switzerland a year ago that the country's order of the PAC-3 MSE version of the guided missiles for Patriot would be delivered later than planned, also in connection with support for Ukraine.