TEHRAN: Foreign envoys toured Sunday a nuclear plant where Iran is enriching uranium in defiance of UN sanctions, a day after Tehran vowed to push ahead “very strongly” with the sensitive work. Iran organized the rare visit in a bid to garner support for its contentious atomic drive ahead of key talks with six world powers in Istanbul next week. The diplomats, among them representatives of some member states of the UN atomic watchdog, the International Atomic Energy Agency (IAEA), saw Iran's heavy water facility at Arak Saturday as part of the tour. Tehran's allies Russia and China snubbed the visit, along with the European Union. Iran's state broadcaster showed footage of the envoys entering the country's main uranium enrichment facility in the central city of Natanz where the material is being refined despite strong objections from the West. “What we have done is an unprecedented move ... to show 100 percent transparency” about Iran's nuclear program, Ali Asghar Soltanieh, Iran's envoy to the IAEA, said on state television from the Natanz facility. The Natanz plant tour comes a day after Iran's atomic chief and Acting Foreign Minister Ali Akbar Salehi vowed to push ahead with the enrichment work “very strongly”, dismissing reports sanctions and technical problems had hampered the nation's nuclear pursuit. Salehi also dismissed reports the program was hit by the Stuxnet computer virus, which the New York Times said Saturday was tested by Israel and the United States on Tehran's nuclear installations. “The Stuxnet issue goes back a year-and-a-half. When they initiated this, they thought we were sleeping ... If this was effective, the IAEA, which regularly inspects (Iranian sites), would have reported the slowdown,” he said. In its online edition, the Times quoted military experts as saying Israel had tested the effectiveness of the Stuxnet computer worm.