TEHRAN, Feb. 26 — The top nuclear officials of Iran and Russia announced today that they had reached initial agreement on a deal to enrich Iranian uranium on Russian soil and said that talks would continue over the details.

The announcement comes as international pressure on Iran to give up its nuclear program has intensified. The governing board of the International Atomic Energy Agency will meet on March 6 to discuss possible punitive measures against Iran, which recently restarted uranium enrichment in defiance of the agency and European and American ultimatums.

The agreement was announced after a meeting between Sergei Kiriyenko, the Russian nuclear chief, and Gholamreza Aghazadeh, the head of Iran"s Atomic Organization in Bushehr, where the Russians built Iran"s first nuclear power plant.

"We held talks with the Russian side on Russia"s proposal yesterday and today," said Mr. Aghazadeh, according to the ISNA student news agency. "The talks saw good progress."

Mr. Kiriyenko said the two countries "have almost no organizational, technical or financial problems" over the proposal. But he said, "It is just an element of a complex approach and more work is needed in the area," ISNA reported.

Iran rejected similar proposals for joint enrichment while it was in negotiations with European nations to halt its program in return for economic concessions. But since those talks broke off, Tehran has alternated between efforts to show that cooperation is still possible and open displays of defiance.

During his weekly news conference today, Hamidreza Assefi, the Iranian Foreign Ministry spokesman, reasserted that Iran had no intention of suspending its nuclear program, which it has insisted is geared toward electricity production instead of weapons.

"We are not worried at all," he said. "We will continue our work and will not suspend our research."