Blasts have been heard in Tehran and sirens have sounded in Israel as US president convenes National Security Council.

Israel and Iran intensified their deadly air strikes Monday on the fifth day after Israel launched its first attack to dismantle Iran's nuclear capability.

Iran has arrested dozens of people on suspicion of spying as fears grow in the Islamic Republic over the extent of its infiltration by Israel’s Mossad intelligence service.

An Iranian state television reporter stopped a live broadcast when an explosion occurred an hour after Israel issued a warning to evacuate the area of Tehran where the TV studios are located.

Since Israel began its concerted attack on Iran on Friday, calls for regime change in Iran have grown louder – from hawks in the US Congress to Israeli officials and some Iranian activists abroad.

State TV says Iran will "attack infrastructure". The broadcaster adds that the military has ordered the evacuation of the headquarters of Israeli TV stations Channel 12 and Channel 14 in response to the attack on the state TV headquarters earlier.

Mohammad-Reza Zafarghandi said in an update that an Israeli strike on Sunday on Quds Square in northern Tehran injured 59 civilians and killed 12 people, including a pregnant woman. That attack also ruptured a main water pipeline.