TEHRAN (Reuters) - Iran has shot down an unmanned US spy plane over its Fordu nuclear site, a state-run website reported on Wednesday, a day after it confirmed it was installing a new generation of advanced uranium enrichment centrifuges. An unmanned US spy plane flying over the holy city of Qom near the uranium enrichment Fordu site was shot down by the Revolutionary Guards air defence units, MP Ali Aghazadeh Dafsari was quoted as saying by the Youth Journalists Clubs website, affiliated to Irans state TV. Other state media did not carry out the report and Iranian officials were not available to comment. The plane ... was trying to collect information about the sites location, he said, without giving details. He did not say when the incident happened. The Fordu site, secretly built inside a mountain bunker near Qom, was acknowledged by Iran only after Western intelligence agencies identified it in 2009. Iranian Foreign Ministry spokesman Ramin Mehmanparast on Tuesday appeared to confirm a Reuters story last week that Iran was installing two more advanced models of the centrifuges used to refine uranium for large-scale testing at a research site. The head of Irans elite Revolutionary Guards announced in January that the Guards had shot down two unmanned western reconnaissance drone aircraft in the Persian Gulf. The Pentagon denied that report but acknowledged some spy planes had crashed in the past due to mechanical failure.