VIENNA, Austria – Iranian officials sent a letter to the U.N. nuclear agency yesterday requesting it remove by mid-month any seals and surveillance systems on their uranium enrichment plant, parts of which were still being monitored by international inspectors. The letter also said Iran would end all voluntary compliance with the U.N. group.

Although Iran broke the seals on its enrichment plant at Natanz on January 10, parts of the plant are still under surveillance by the International Atomic Energy Agency.

Iran had been complying voluntarily with a set of rules that allows inspections on short notice and the monitoring of many facilities, such as manufacturing plants, that make parts for its nuclear program. With voluntary compliance now being terminated, access to those facilities as well as snap inspections will end.

The moves follow a vote Saturday by the 35-member IAEA to report Iran to the U.N. Security Council over Tehran’s nuclear program.

The nuclear agency had many outstanding questions about Iran’s nuclear program and wanted more information about several locations where Iran is suspected of pursuing nuclear and weapons related research. But without the voluntary cooperation, it is unlikely inspectors will get the answers.

According to the letter sent to the IAEA, a copy of which was obtained by the Los Angeles Times, “all the agency’s containment and surveillance measures which were in place beyond the normal agency safeguards measures should be removed by mid-February 2006.”

The letter states that Iran is obligated to take these steps because of a law passed by its parliament in November that says the country must end voluntary compliance and restart uranium enrichment if it is referred to the Security Council.

Diplomats close to the IAEA said inspectors would travel to Iran in the next several days to remove any remaining seals and surveillance measures such as security cameras, except for those that are required under the Nuclear Nonproliferation Treaty, of which Iran is a signatory. That means there will be far more limited inspections by the IAEA, and those inspections will have to be scheduled well in advance.

Although the letter merely makes good on threats Tehran has voiced for weeks, it represents Iran’s official decision, in the wake of the agency’s weekend emergency meeting, to thwart the will of the international community.

The resolution reporting Iran requires Tehran to cooperate with the IAEA and reinstate a full suspension of all uranium-enrichment activities, which could provide fuel for civilian nuclear power but also material for a nuclear weapon.

The IAEA oversees two nuclear inspection regimes: safeguards under the Nuclear Nonproliferation Treaty and under an “additional protocol.”

Under the safeguard rules, the IAEA keeps track of enriched uranium and plutonium. Countries that are signatories of the treaty must inform the agency whenever they are processing uranium or using it for electrical power plants or other purposes so that is strictly monitored.

It is possible to perfect the technology necessary to enrich uranium for peaceful purposes, secretly move toward a weapons program and then withdraw from the treaty and make bombs – the course taken by North Korea in 2002.

Concerned that the Nuclear Nonproliferation Treaty did not offer sufficient protections, the agency’s members drafted an additional protocol. If signed by a country, the measure gives the IAEA broad access to facilities connected to a country’s nuclear program, including manufacturing plants where the machinery is made for enriching uranium. With knowledge of how far along a country has gone toward developing its enrichment technology, weapons inspectors can give a sound assessment of the country’s likelihood of being able to make a nuclear bomb.

So far 106 countries have ratified the additional protocol.Iran had not signed on, but had been complying voluntarily.With that cooperation ended, it will be harder to keep tabs on Iran’s nuclear activities, according to nonproliferation experts.

“The agency will simply not have the same ability to provide the international community with information about Iran’s preparations to manufacture nuclear material. … It becomes a black hole,” a former special representative of the president for nonproliferation at the State Department, Norman Wulf, said.

“What’s of most concern to the United States and its European allies right now is Iran’s nuclear capability, so the right to look at these [manufacturing] facilities is extremely important at this stage,” Mr. Wulf added.

The limits on inspections also will make it more difficult for Iran to prove that its program is peaceful, as it has claimed, several diplomats noted.