Russia also agreed not to provide an enrichment plant and terminated cooperation on several other nuclear-related technologies, including laser isotope separation.

Since Iran-Iraq war ended in 1988, Iran's revolutionary leaders have actively sought nuclear-related technology from countries like China, India, Argentina, Pakistan and Germany.

Iran is aggressively shopping for nuclear-related technology, including equipment like computers and fuses, and has tried to attract nuclear scientists to Iran, foreign diplomats in Teheran say.

It banned the supply of nuclear-related technology and materials and froze the assets of key individuals and companies related to the enrichment program.

Russia has provided Teheran with nuclear-related technologies, missile components and other advanced equipment.

Those penalties would probably include a ban on travel by Iranian officials and curbs on imports of nuclear-related technology.

Its former chief nuclear scientist, Abdul Qadeer Khan, formed a global nuclear network that investigators say supplied Iran, North Korea and Libya with nuclear-related technology.

The Administration had asked China to limit future shipments of nuclear-related technology and equipment to Pakistan, suggesting that in return it could waive some economic sanctions under consideration.

The increasing focus on Iran has shed light on the clandestine routes it has used to obtain nuclear-related technology to advance its enrichment program.

Between 1988 and 1990, for instance, of the 410 applications that U.S. companies filed to export nuclear-related technology to Iraq, only 5 percent were turned down.