Ahmadinejad's senior advisor Mojtaba Samareh Hashemi told the ILNA news agency that the hardliner had "approved the locations of the new nuclear sites" and the "construction at these sites will start with his order."
He said that the designs of the new plants were currently under study but did not specify how many new facilities had been approved.
In November 2009, a defiant Ahmadinejad announced that Iran would build 10 new uranium enrichment plants after Tehran was censured by the UN nuclear watchdog for constructing its second such facility near the Shiite shrine city of Qom.
Iran currently enriches uranium at a plant in the central city of Natanz in defiance of repeated UN Security Council ultimatums to suspend the sensitive process.
In April, Iran's atomic chief Ali Akbar Salehi said that plans for two new enrichment plants had been submitted to Ahmadinejad and their construction would start in the first half of the Iranian year, which runs to March 2011.
Iran is already under three sets of UN sanctions and the possibility of a fourth looms large as Washington steps up efforts to secure agreement at the Security Council.
The five veto-wielding permanent members Britain, China, France, Russia and the United States are currently engaged in intense negotiations over the details of a new package.
China, which has emerged as Iran's main economic partner in recent years, is still insisting on a diplomatic solution to the crisis.
The standoff worsened after talks between the major powers and Iran failed to produce agreement on proposals for the supply of nuclear fuel drafted by the UN nuclear watchdog in October last year.
The deal envisaged Iran shipping its low-enriched uranium abroad in return for the supply by Russia and France of the higher-enriched uranium fuel required for a Tehran medical research reactor.
But the negotiations ran into difficulty after Iran insisted that the exchange happen simultaneously and on its own soil, conditions rejected by the major powers.
Iranian Foreign Minister Manouchehr Mottaki insisted on Sunday that a deal could still be done in "two weeks" if there was the diplomatic will.
He said Iran planned to open negotiations with all 15 members of the UN Security Council in seach of an agreement.
"In the coming days, we have plans to have direct talks with 14 members of the Security Council and one (set of) indirect talks with a member," he said, in reference to Washington, which does not have diplomatic ties with Tehran.
"The talks will focus on the fuel exchange. They will be conducted by Iran's missions in those countries," he told a press conference after a two-day nuclear disarmament conference hosted by Tehran.
Mottaki's remarks are not expected to assuage the growing exasperation of Western governments, who are still furious over Iran's decision to start enriching uranium itself in February to the 20-percent level required by the Tehran research reactor.
Washington has argued repeatedly that only a new round of sanctions will persuade Tehran to enter serious negotiations.