Iran’s top nuclear negotiator Sunday said it is “impossible” for Tehran to yield to the key Western demand over its nuclear program, even if the UN Security Council imposes further sanctions.

The chief of the UN nuclear watchdog Mohamed ElBaradei will tell nations on its governing board this week Iran’s pledge of extra atomic transparency should be given a chance to work, not dismissed as a time-buying ruse.

Iranian Foreign Ministry Spokesman Seyed Mohammad Ali Hosseini stressed his country’s insistence on the right to access civilian nuclear technology for peaceful purposes, underlining that Tehran has not changed its nuclear stances.