Negotiators from the United States and Iran were set to start peace talks in Switzerland on Sunday, even as US officials disputed Iranian claims about closing the key Strait of Hormuz.A high-level Iranian team arrived in Switzerland for peace talks with the US, Iranian state media reported, as US Vice President JD Vance departed Washington for meetings that Pakistan said will begin on Sunday.

Although the US and Iran had agreed to a 60-day ceasefire while negotiations take place, Tehran's Islamic Revolutionary Guard Corps on Saturday declared the Strait of Hormuz shut, though the US military said commercial vessels had continued operating in the waterway.

Those developments could complicate talks in which both sides seek to advance an interim deal brokered by Pakistan and signed on Wednesday by US President Donald Trump and Iranian President Masoud Pezeshkian to end their almost four-month war.

Pointing to what it called Israeli "crimes" in Lebanon that violated US commitments to a ceasefire, the IRGC warned ships would be at risk if they approached the Strait, a vital conduit for global oil and gas supplies. But US Central Command said 55 merchant ships transited the strait on Saturday with more than 17 million barrels of oil for global markets.