Explosions heard in Tehran as Israel says it's targeted Iran nuclear sites and military

Israel attacked Iran's capital early Friday, with explosions booming across Tehran as Israel said it targeted the country's nuclear and military sites.

The attack comes as tensions have reached new heights over Tehran's rapidly advancing nuclear program. The Board of Governors at the International Atomic Energy Agency for the first time in 20 years on Thursday censured Iran over the country's refusal to work with its inspectors. Iran immediately announced it would establish a third enrichment site in the country and swap out some centrifuges for more-advanced ones.

Israel for years has warned it will not allow Iran to build a nuclear weapon, something Tehran insists it doesn't want — though officials there have repeatedly warned it could. The U.S. has been preparing for something to happen, already pulling some diplomats from Iraq's capital and offering voluntary evacuations for the families of U.S. troops in the wider Middle East.

Israeli Prime Minister Benjamin Netanyahu said in an address on YouTube that the attacks will continue "for as many days at it takes to remove this threat."

U.S. Secretary of State Marco Rubio said Israel took "unilateral action against Iran" and that Israel advised the U.S. that it believed the strikes were necessary for its self-defence.

"We are not involved in strikes against Iran and our top priority is protecting American forces in the region," Rubio said in a statement released by the White House.

Rubio also issued a warning to Iran that it should not target U.S. interests or personnel.

People in Tehran awoke to the sound of the explosion, and State television acknowledged the blast. Both Iran and Israel closed their airspace.

It wasn't immediately clear what had been hit, though smoke could be rising from Chitgar, a neighbourhood in western Tehran. There are no known nuclear sites in that area — but it also wasn't clear if anything was happening in the rest of the country.

An Israeli military official, who spoke to journalists on the condition of anonymity to discuss the ongoing operation, which is also targeting military sites, said that his country targeted Iranian nuclear sites, without identifying them.

Defence Minister Israel Katz said Israel had carried out the attack, without saying what it targeted.

"In the wake of the state of Israel's preventive attack against Iran, missile and drone attacks against Israel and its civilian population are expected immediately," he said in a statement.

The statement added that Katz "signed a special order declaring an emergency situation in the home front."

"It is essential to listen to instructions from the home front command and authorities to stay in protected areas," it said.