Negotiations take place as US builds naval presence in region and in aftermath of bloody crackdown on protesters

Iran and US nuclear talks – live updates

The US and Iran are due to start high-stakes talks in Oman over Tehran’s nuclear programme that are being seen as representing one of the last chances to prevent a new US attack.

The negotiations are the first since the US struck Iranian nuclear targets in June, joining in the final stages of a 12-day Israeli bombing campaign.

Washington wants to expand the talks to cover Iran’s ballistic missiles, support for armed groups around the region and “treatment of their own people” – as the US secretary of state, Marco Rubio, said on Wednesday – but after days of speculation Iranian negotiators are satisfied that only the nuclear dispute will be discussed, at least initially.