United Nations Secretary-General Antonio Guterres called on the American and Iranian sides to exercise 'maximum restraint' and urgently return to the negotiating table.

Stephane Dujarric, spokesman for the UN Secretary-General, said in a statement on Sunday that Guterres is 'deeply concerned about the major escalation and resumption of military confrontations in the Gulf,' calling on all parties to 'exercise maximum restraint' and 'urgently resume negotiations' to avoid widening the conflict.

Guterres stressed that 'a return to large-scale hostilities would have grave consequences for the peoples of the region, for international peace and security, and for the global economy.'

Explosions rocked several areas in southern Iran on Sunday, following new U.S. military strikes targeting Iranian missile and air defense systems, according to Axios citing a U.S. official.

Hours earlier, the U.S. military announced one of the largest air and sea operations against targets inside Iran in recent days, involving more than 300 military sites, in response to attacks on commercial vessels in the Strait of Hormuz.