"Indirect negotiations between Iran and the United States are set to be held on Friday in Muscat," said the Tasnim news agency, adding that they "will be limited to the nuclear issue and the lifting of sanctions on Iran".

ISNA news agency carried a similar report, saying Foreign Minister Abbas Araghchi will head the Iranian delegation, which will also include senior diplomats Majid Takht-Ravanchi and Kazem Gharibabadi.

US envoy Steve Witkoff will represent Washington in the talks, ISNA added, noting that President Donald Trump's son-in-law Jared Kushner may also be present.

Tehran has repeatedly stressed that talks should remain focused solely on the nuclear issue, rejecting negotiations over its missile programme or defence capabilities.

Araghchi and Witkoff led five rounds of nuclear talks between Iran and the United States last year before negotiations were derailed when Israel launched an unprecedented bombing campaign two days ahead of a planned sixth round, triggering a 12-day war.

Friday's talks will be held amid heightened tensions between Tehran and Washington, as the United States has in recent days deployed an aircraft carrier group to the Middle East following a crackdown on anti-government protests.

Tehran has acknowledged more than 3,000 deaths during the unrest, which Iranian authorities said began as peaceful protests before turning into "riots" involving killings and vandalism and inflamed by its arch-foes the United States and Israel.

The Human Rights Activists News Agency, a US-based NGO, said it has confirmed 6,872 deaths, mostly protesters killed by security forces, with other rights groups warning the figure is likely far higher.