Tel Aviv/Tehran: Israeli strikes in Iran have killed at least 406 people and wounded 654 others, a human rights group said on Sunday.

While Israel threatened even greater force even as its airstrikes entered third day on Sunday, some Iranian missiles evaded Israeli air defences to strike buildings in the heart of the country.

Also, the planned talks on Iran's nuclear programme, which could provide an off-ramp, were cancelled.

The region braced for a protracted conflict after Israel's surprise bombardment of Iran's nuclear and military sites on Friday killed several top generals and nuclear scientists, and neither side showed any sign of backing down.

Iran said Israel struck two oil refineries, raising the prospect of a broader assault on Iran's heavily sanctioned energy industry that could affect global markets. The Israeli military, in a social media post, warned Iranians to evacuate arms factories, signalling what could be a further widening of the campaign. Around noon local time, explosions were heard again in the Iranian capital, Tehran.

US President Donald Trump has expressed full support for Israel's actions while warning Iran that it can only avoid further destruction by agreeing to a new nuclear deal.

Iranian Foreign Minister Abbas Araghchi said on Sunday that if the Israeli strikes on Iran stop, then “our responses will also stop". He said the United States "is a partner in these attacks and must take responsibility".

Explosions in Tehran New explosions echoed across Tehran and were reported elsewhere in the country early Sunday, but there was no update to a death toll released the day before by Iran's UN ambassador, who said 78 people had been killed and more than 320 wounded.

In Israel, at least 10 people were killed in Iranian strikes overnight and into Sunday, according to Israel's Magen David Adom rescue service, bringing the country's total death toll to 13. The country's main international airport and airspace remained closed for a third day. Israeli strikes targeted Iran's Defence Ministry early Sunday after hitting air defences, military bases and sites associated with its nuclear programme.