Differences over the scope for the talks have also cast doubts on whether it will still go ahead, keeping open the risk of U.S. military action.

DUBAI/WASHINGTON, Feb 6 (Reuters) - Iran and the United States are set to hold high-stakes negotiations in Oman on Friday over Tehran's nuclear programme, but a dispute over the agenda suggests progress will be hard won amid the threat of a regional Middle East war.

Ayatollah Ali Khamenei, Iran’s supreme leader, has vowed to unleash a regional war if America launches air strikes. Initially few in the Middle East seemed eager for further conflict. The region’s power-brokers tried to dissuade America from military action. But attitudes now look more mixed.

As EU designates Iran's IRGC as terrorist group, pressure mounts on U.K. to act as London center allegedly promoting Iranian regime propaganda.

The authorities are making mass arrests, seizing assets and hunting down doctors who treated protesters. Some Iranians keep showing defiance anyway.

Oil futures gave back gains from the previous session on lower risk premium with talks between the U.S. and Iran set to take place Friday in Oman.

Iran requested to move talks from Turkey, Secretary of State Rubio confirms. Rubio laid out what topics needed to be discussed for a "meaningful" result.