The United States and Israel have launched an attack on Iran, with explosions heard and seen across Tehran, as Israel announced it had conducted a missile strike on the country.

Several missiles struck University Street and the Jomhouri area in Tehran, according to the Fars news agency. Smoke was seen rising in the city, an Al Jazeera correspondent reported.

A US official told Al Jazeera that the attacks were carried out as a joint military operation with the United States, which has assembled a large fleet of fighter jets and warships in the region to pressure Iran over its nuclear program.

The Associated Press reported that the strike in Iran's capital occurred near offices of Supreme Leader Ayatollah Ali Khamenei.

Iran's semi-official Tasnim news agency reported explosions also occurred in Tehran's northern Seyyed Khandan area.

Israel's Defence Minister Israel Katz described the attack as "preemptive" to "remove threats to the State of Israel."

As sirens sounded in Israel, the military said it had issued a "proactive alert to prepare the public for the possibility of missiles being launched toward the state of Israel."

Israel's Airports Authority announced airspace had been closed to all civilian flights and urged the public not to come to the airport.

Meanwhile, the US Embassy in Qatar implemented shelter-in-place for all personnel, recommending that all its citizens do the same until further notice.

Source: www.aljazeera.com