Meanwhile Donald Trump says his early G7 exit has "nothing to do" with an Israel-Iran ceasefire, as fighting between the two nations enters a fifth day.

Fresh explosions were reported in the Iranian capital of Tehran on Sunday afternoon local time after Iran's president warned of "more painful and crushing responses" to Israeli strikes.Footage circulating online on Sunday afternoon Tehran time appeared to show smoke rising from buildings in several locations and at least one video of a burning car.

Later Monday, Trump posted on his social media site an ominous message calling for the immediate evacuation of Tehran, Iran’s capital. He made the post while in Canada attending the G7 summit.

US President Donald Trump has published a series of harsh posts against the Iranian regime and decided to leave the G7 summit a day early "for the sake of important Middle East issues". There are loud explosions in Tehran and huge traffic jams on the city's exits, Details wrote.

The retaliatory strikes came on Saturday, a day after Israel killed top Iranian military leaders and scientists and destroyed an aboveground nuclear enrichment plant near Natanz.

Israel has reportedly carried out a pre-emptive strike targeting sites in Iran, according to Israeli media outlet Channel 12. The attack comes amid heightened regional tensions, with Al Jazeera reporting loud explosions in Tehran shortly after the strike. Axios also confirmed that air raid sirens were heard across multiple locations in Israel.

Loud blasts were heard Monday in western Tehran as a rapidly escalating air war between Iran and Israel raged for the fourth consecutive day.

Iran’s state-run news agency said Monday that its governmental television station abruptly stopped a live broadcast after an Israeli strike.