The Islamic republic organised the rare visit in a bid togarner support for its contentious atomic drive ahead of keytalks with six world powers in Istanbul next week.
The diplomats, among them representatives of some memberstates of the UN atomic watchdog, the International AtomicEnergy Agency (IAEA), saw Iran''s heavy water facility at Arakyesterday as part of the tour.
Tehran''s allies Russia and China snubbed the visit, alongwith the European Union.
Iran''s state broadcaster showed footage of the envoysentering the country''s main uranium enrichment facility in thecentral city of Natanz where the material is being refineddespite strong objections from the West.
"What we have done is an unprecedented move... to show100 per cent transparency" about Iran''s nuclear programme, AliAsghar Soltanieh, Iran''s envoy to the IAEA, said on statetelevision from the Natanz facility.
The Natanz plant tour comes a day after Iran''s atomicchief and acting foreign minister, Ali Akbar Salehi, vowed topush ahead with the enrichment work "very strongly",dismissing reports sanctions and technical problems hadhampered the nation''s nuclear pursuit.
"The recent sanctions did not create any problems for ournuclear activities," Salehi told a news conference in Arakbroadcast live on state television.
"Our nuclear activities are going forward strongly. Ouractivities, especially in (uranium) enrichment, are alsocontinuing very strongly... The production of enriched uraniumis growing."
Salehi''s remarks were seen as Tehran''s response tocomments by US Secretary of State Hillary Clinton last weekwhen she asserted Iran''s nuclear programme had been hit bysanctions.
"They have made it much more difficult for Iran to pursueits nuclear ambitions," she said. "Iran has technologicalproblems that have made it slow down its timetable."
Salehi also dismissed reports the programme was hit bythe Stuxnet computer virus, which the New York Times said onSaturday was tested by Israel and the United States onTehran''s nuclear installations.
"The Stuxnet issue goes back a year and a half. When theyinitiated this, they thought we were sleeping... If this waseffective, the IAEA, which regularly inspects (Iranian sites),would have reported the slowdown," he said. (AFP)