Tehran, Iran ? Iran confirmed for the first time Monday that it converted 37 tons of raw uranium into gas, a key step ahead of enrichment, before it suspended all such activities in November under international pressure.

The confirmation means Tehran is in a position to quickly start enriching uranium if it chooses to end its suspension of enrichment-related activities. It comes at a crucial time, with Europe trying in fragile negotiations to seal an agreement to ensure that Iran’s nuclear program does not produce weapons.

The Europeans agreed last year that Iran could finish converting the 37 tons. Iran had begun processing the material in a rushed attempt to do it just before the suspension.

Mohammad Saeedi, deputy head of the Atomic Energy Organization of Iran, told The Associated Press that Iran had processed the uranium into UF-4 gas. If processed further into UF-6, the material could be fed into centrifuges and enriched, allowing it to be used either to produce electricity or make nuclear weapons.

“We converted all the 37 tons of uranium concentrate known as yellowcake into UF-4 at the Isfahan Uranium Conversion Facility before we suspended work there,” Saeedi said.

Nuclear experts say that when fully processed, the 37 tons of yellowcake can theoretically yield more than 200 pounds of weapons-grade uranium, enough to make five crude nuclear weapons.

The United States accuses Iran of seeking to develop weapons, while Tehran insists its nuclear program aims only to produce electricity. To avoid referral to the U.N. Security Council for possible sanctions, Iran agreed to suspend actual enrichment at its Natanz uranium enrichment plant in 2003.

To bolster international confidence, Tehran in late 2004 suspended other uranium enrichment-related activities — including the conversion of yellowcake into gas and the building of centrifuges.

Natanz and the uranium conversion facility in Isfahan house the heart of Iran’s nuclear program. The Isfahan conversion facility reprocesses uranium ore concentrate into gas, which is taken to Natanz and fed into centrifuges for enrichment.

To show its dissatisfaction with lack of progress in nuclear talks between Iran and the key European powers, Foreign Ministry spokesman Hamid Reza Asefi said Sunday that Iran has decided to resume some uranium reprocessing activities.

Saeedi said that may happen in the next two or three days.

Negotiations between Iran and France, Britain and Germany over Tehran’s nuclear program deadlocked last month, as the Europeans pressed for a complete end to Iran’s enrichment program in return for economic incentives.

Iran insists it has the right to carry out enrichment and has warned that if talks collapse, it could resume its program.