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.