TEHRAN, Iran - Iran's Revolutionary Guard shot down an unmanned US spy plane that was trying to gather information on an underground uranium enrichment site, a state-owned news site said Wednesday.

Lawmaker Ali Aghazadeh Dafsari said the drone was flying over the Fordo uranium enrichment site near the holy city of Qom in central Iran, the state TV-run Youth Journalists Club said.

The report did not say when the plane was shot down.

Iran is locked in a dispute with the US and its allies over Tehran's disputed nuclear program, which the West believes aims to develop nuclear weapons. Iran denies the accusations, saying its nuclear program is aimed at generating electricity and producing isotopes to treat medical patients.

Long kept secret, the Fordo site is built next to a military complex to protect it in case of attack. Iran only acknowledged Fordo's existence after Western intelligence agencies identified it in September 2009. The facility is reportedly located 295 feet (90 meters) underneath a mountain.

Iran says it is planning to install advanced centrifuges at Fordo to speed up its nuclear activities.

US nuclear experts say by increasing the enrichment level and its stock of nearly 20 percent low-enriched uranium, Iran could reach a "break out" capability that would allow it to make enough weapon-grade uranium for a nuclear weapon.

Iran has claimed to shoot down US spy planes in the past. Earlier this month, Iranian military officials showed Russian experts several US drones they said were shot down in recent years.