Iran's chief nuclear negotiator said on Tuesday the Vienna talks were moving forward despite difficulties but warned Tehran would stop the negotiations if faced with "unreasonable demands" or time-wasting.
"Abbas Araqchi ... assessed the current trend of the talks as going forward, despite the existing difficulties and challenges," Iranian state media reported.
"The Iranian delegation will stop the talks whenever the process of negotiations leads to unreasonable demands, waste of time and irrational bargaining," Araqchi was quoted as saying.