TEHRAN — Iran’s nuclear chief, reversing the country’s previous statements, said on state television on Sunday that the country would not halt its production of higher-grade uranium, suggesting that the Iranian government was veering back to a much harder line after talks in Baghdad with the West last week ended badly.

The official, Fereydoon Abbasi, said there would be no suspension of enrichment by Iran, the central requirement of several United Nations Security Council resolutions. He specifically said that applied to uranium being enriched to 20 percent purity — a steppingstone that puts it in fairly easy reach of producing highly enriched uranium that can be used for nuclear weapons.

“We have no reason to retreat from producing the 20 percent, because we need 20 percent uranium just as much to meet our needs,” Mr. Abbasi said, according to Iranian state television.

Mr. Abbasi’s statement will be of particular concern to the United States and Israel because Iran is producing more of its 20 percent enriched uranium in a deep underground site that is considered highly resistant to bombing. The site, called Fordow, is on a military base and was discovered by Western intelligence agencies several years ago, but Iran only acknowledged the work there in 2009.

The Fordow plant, near the holy city of Qum, is so deep that Israeli officials say if Iran makes progress there, it will have entered a “zone of immunity” where it would be safe from Israeli or American military action. Getting Iran to halt its 20 percent enrichment, and ultimately dismantle and close the Fordow plant, has been described by American officials as their top priority.

Mr. Abbasi’s remarks, which included an announcement that Iran would start building two nuclear power plants in 2013, are bound to complicate the already difficult nuclear talks between Iran and the world powers, which are to be continued in Moscow on June 18. If the talks fail, the powers are planning to tighten sanctions on Iranian exports and financial dealings as early as July 1, including placing an embargo on all sales of Iranian oil to Europe.

Iran’s enrichment of uranium is at the center of those discussions, with Western countries suspecting the country of stockpiling enriched uranium that could be rapidly converted into weapons-grade material. Iran says it only wants to produce civilian nuclear energy.

Before the meeting in Baghdad, Mr. Abbasi had hinted that Iran was ready to compromise on its program of enriching uranium up to 20 percent with the isotope capable of sustaining nuclear fission, which it says it needs to fuel an aging United States-designed medical reactor.

Iranian negotiators were under the impression that the Obama administration and its allies, in return, were willing to allow Iran to continue to enrich up to a lower percentage. But during the Baghdad meeting it became clear that such an offer was not on the table, at least for now.

Instead, the world powers offered another proposal, which called for Iran to export its stockpile of the more highly enriched uranium and suspend any further production. In exchange, the country was to receive supplies of medical isotopes.

That plan was turned down by Iran’s negotiators, who made a counterproposal that would have allowed Iran to continue to enrich uranium. It also called for nuclear disarmament and, among other things, cooperation in the fight against Somali pirates in the Horn of Africa.

Both sides expect the other to take the first significant steps, without wanting to compromise on critical issues, said a European diplomat familiar with the talks.

Iranian officials have been unclear about how much of the higher enriched uranium they want to produce. A Friday report by the International Atomic Energy Agency said that Iran had produced 145 kilograms of uranium enriched up to 20 percent, more than it ordered from Argentina in 1988, the last time it needed a stockpile for its medical reactor. In other words, it has already made enough to keep its reactor, which produces medical isotopes, running for another two decades. Iran’s insistence on producing more — though it has no reactor to burn the additional fuel — has increased suspicions about its intentions.

In April, Mr. Abbasi said that Iran planned to build five more medical reactors, and that it needed to create a stockpile of fuel for that purpose.

Western powers fear that Iran, if needed, could quickly enrich the uranium to weapons-grade levels of 90 percent or above. But that would require a repiping of its equipment and would most likely be detected by the energy agency’s inspectors.

The energy agency’s report also said that in one instance uranium enriched up to 27 percent was found. Mr. Abbasi said it was a technical or operational mistake. Western experts on Friday agreed that such an explanation was plausible.

President Mahmoud Ahmadinejad of Iran, who has been largely sidelined in the nuclear talks by Iran’s supreme leader, Ayatollah Ali Khamenei, urged the country’s Parliament on Sunday to stand with him against the “evil ones” who he said had encircled the nation.

On Saturday, Mr. Abbasi, a former nuclear scientist who survived an assassination attempt two years ago that is believed to have been mounted by Israel, also highlighted complications in the talks with the energy agency, which took place in Tehran two days before the meeting with the world powers.

After the talks wrapped up, the energy agency’s secretary general, Yukiya Amano, who had flown to Tehran for the first time since his appointment in 2009, said that he was near an agreement with the Iranians on extra inspections, including at Parchin, a military base near the capital where the agency suspects military nuclear activities are under way.

Iran’s nuclear chief made clear that such an agreement would only be signed if the agency presented evidence that proved Iran was pursuing illegal nuclear activities on the site.

“The reasons and documents have still not been presented by the agency to convince us to give permission for this visit,” Mr. Abbasi was quoted as saying by the Fars news agency on Saturday. David E. Sanger contributed reporting. (Copyright 2012 The New York Times Company 05/28/12)