Following are the facilities considered to be the main sites dedicated to Iran's nuclear drive. These and other related sites have been declared to the International Atomic Energy Agency (IAEA) and are currently subject to constant supervision.

MINING:

In Saghand, near the central desert oasis city of Yazd, Iran has discovered and is mining huge deposits of uranium ore -- meaning the Islamic republic can be self-sufficient from the very start of the nuclear fuel cycle.

CONVERSION:

Raw mined uranium, or "yellowcake", is then transferred to a Uranium Conversion Facility (UCF) at the foot of the mountains on the edge of the central city of Isfahan, the ancient capital of Persia.

The mined uranium is transformed into uranium tetrafluoride (UF4) and then into uranium hexafluoride (UF6), a feed gas for the actual process of enrichment.

The vast site covers more than 1,000 square kilometers (400 square miles) and its functionality was tested in 2004 before Tehran ordered a voluntary suspension of its nuclear activities.

The European Union says that the best guarantee Iran can offer that it is not pursuing the bomb is to definitively cease all enrichment-linked activity, including conversion.

Protected by a battery of anti-aircraft guns, work as the vast facility had been suspended up until now as Iran pursued talks with the European Union over its nuclear programme.

Iran had accepted to suspend enrichment in October 2003 but the IAEA persuaded it to suspend all activity linked to the practice, like conversion and the construction of centrifuges.

However the IAEA allowed Iran to convert 37 tonnes of yellowcake in 2004 under its supervision for experimental purposes before the practice was suspended.

ENRICHMENT:

Iran has build a massive underground complex near the central town of Natanz. The facility is designed to host cascades of thousands of centrifuges. UF6 gas is fed into the centrifuges, which spin at supersonic speeds to enrich the uranium.

Iran says it only wishes to enrich to the low level purity required for reactor fuel. However, the process could potentially be diverted to produce weapons grade uranium.

Natanz is particularly controversial: Iran only declared the facility to the International Atomic Energy Agency (IAEA), the UN's nuclear watchdog, after the site was exposed in 2002 by an exiled opposition group.

Iran has also admitted to buying key centrifuge components through a black market ring run by the disgraced father of Pakistan's nuclear bomb, Abdul Qadeer Khan.

Officials recently allowed foreign journalists to visit the site in a gesture of transparency. It is ringed by scores of anti-aircraft guns.

HEAVY WATER REACTOR:

Iran has begun building a heavy water research reactor in Arak, a site around 250 kilometers south of Tehran that was also exposed by the exiled opposition.

The IAEA is concerned about the proliferation risk as the reactor could produce 8-10 kilograms (about 20 pounds) of plutonium a year, enough to make at least one nuclear bomb.

The construction of the reactor could be completed by 2009.

POWER PLANT:

The construction of Iran's atomic power plant near the southern coastal city of Bushehr is nearing completion.

The project was first launched by the former shah of Iran, Mohammad Reza Pahlavi, in the 1970s but stalled due to the 1979 Islamic revolution and the 1980-88 Iran-Iraq war.

In the early 1990s Iran began to search for help to revive the project, and in 1995 found help from Russia. Russia has also agreed to fuel the plant and bring it on line in 2006, but the fuel supply deal commits Iran to returning any spent material.

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