A team of UN inspectors has arrived in Iran to visit a controversial uranium enrichment plant near the town of Qom.
The four scientists were due to inspect the facility on Sunday, as Western powers waited for Iran's reply to a UN-backed proposal which could see its uranium shipped overseas for enrichment.
UN inspectors have arrived in Iran where they are due to visit a previously secret nuclear facility.
The plant is near the city of Qom and the UN officials are expected to remain in the country for three days.