The statement by Ali Akbar Salehi on Sunday evening comes after President Mahmoud Ahmadinejad earlier in the day instructed Iran's Atomic Energy Organization to start work on producing higher-grade nuclear fuel for a Tehran reactor.
Iran's announcement raised the stakes in its dispute with the West, but Ahmadinejad said talks were still possible on a nuclear swap offer by world powers designed to allay fears the Islamic Republic is making an atomic bomb.
Salehi, who heads the Atomic Energy Organization, also on Sunday said Iran would start producing uranium enriched to a level of 20 percent on Tuesday, in the presence of inspectors from the International Atomic Energy Agency (IAEA).
He said Iran will formally inform the Vienna-based UN agency about the move in a letter on Monday, Iran's Arabic-language television station al Alam reported. He earlier said production would take place at Iran's Natanz site.
But Salehi also suggested production would be halted if Iran received fuel enriched to 20 percent from abroad. Iran has expressed readiness to exchange its low-enriched uranium for higher-grade fuel, but wants amendments to the UN-drafted plan.
"Iran would halt its enrichment process for the Tehran research reactor any time it receives the necessary fuel for it," Salehi said.
Iran in November announced plans to build 10 new enrichment plants in a major expansion of its atomic program, but did not specify the timeframe. The West fears Iran's nuclear work is aimed at making bombs. Tehran denies the charge.
"Iran will set up 10 uranium enrichment centers next year," al Alam quoted Salehi as saying. The Iranian year starts on March 21.
Analysts have expressed skepticism whether sanctions-bound Iran, which has problems obtaining materials and components abroad, would be able to equip and operate 10 new plants.
Enriched uranium can be used as fuel for nuclear power plants and, if refined much further, provide material for bombs. Iran currently enriches uranium to a level of 3.5%. A nuclear bomb would require 80 percent or more.