Iran has built an unmanned surveillance aircraft with a range of more than 600 miles - enough to reach Israel - a top defense official said in remarks published Wednesday.

Deputy Defense Minister Ahmad Vahidi said he could not provide more details, only saying the development of the unmanned aircraft, or drone, was an "important achievement." His remarks were published Wednesday in the government-owned newspaper, Iran, and by the semiofficial Fars news agency.

Iran announced two years ago it had built an unmanned aircraft, but Vahidi''s comments were the first by a top official revealing its range. His claims could not be independently confirmed.

Wednesday''s reports follow this week''s announcement that Iran has restructured its military in an effort to improve its air defense capabilities.

The move was widely seen as part of a broader military build up by Tehran, which is concerned about the U.S. military''s presence in neighboring Iraq and Afghanistan and Israeli threats to target its nuclear facilities.

Iran has taken Israeli threats to strike its nuclear sites seriously and has said Israel would be subject to Iran''s "devastating retaliation" if it attacks.

The first word of the drone came in 2007, when the then-commander of the Revolutionary Guards, Gen. Yahya Rahim Safavi, said the unmanned device was designed to take photos of and gather information about enemy positions.

Iran also is seeking to develop a drone with attack capabilities.