Arab coalition nations have resumed air strikes against Houthi fighters in Yemen as a UN envoy called for an extension of a five-day humanitarian ceasefire that expired late Sunday.

The coalition targeted Houthi rebel positions in al-Sawlaban and al-Arish in Aden province, Saudi military officials said early on Monday.

Al-Masirah TV, a Houthi-backed channel, reported that Saudi troops were also shelling al-Manzala district in al-Dalih near the Yemen-Saudi border, in addition to Al-Ghawr mountain.

“I call on all parties to renew their commitment to this truce for five more days at least,” UN envoy to Yemen Ismail Ould Cheikh Ahmed said earlier in Riyadh. “This humanitarian truce should turn into a permanent ceasefire.”

His appeal followed clashes between rebels and pro-government forces across south Yemen on Saturday despite the truce, which has largely held since starting on Tuesday at 2000 GMT.

Speaking in Seoul on Monday, US Secretary of State John Kerry said the US continues to support the idea of a humanitarian ceasefire in Yemen, but that such a truce was difficult given the current circumstances.

The official Saudi Press Agency, meanwhile, reported that the UN envoy met Saudi chief of staff Lieutenant General Abdulrahman bin Saleh al-Bunyan and discussed “humanitarian aid efforts” in Yemen.

Aid groups have called for a lasting truce in the impoverished country, where a Saudi-led regional coalition has waged an air war Houthis and their allies since late March.

Yemeni political parties began talks on Sunday in the Saudi capital aimed at finding a solution to the crisis. But the Houthis stayed away from the meeting of some 400 delegates, including President Abd-Rabbu Mansour Hadi, who has taken refuge in Riyadh.

Hadi repeated accusations that the rebels had staged a “coup”.

“We are trying to regain our nation” from militias backed by “external” forces, he said in a reference to Iran, which has denied arming the rebels.

An Iranian aid ship bound for Yemen in defiance of US warnings has entered the Gulf of Aden and is expected to dock on Thursday, media in Tehran reported.

Clashes in Aden

Its mission has been overshadowed by US calls for it to head to a UN emergency relief hub in Djibouti instead of the Yemeni port of Hodeida.

Clashes raged overnight Saturday in the central city of Taiz between Houthis – supported by troops loyal to ousted president Ali Abdullah Saleh – and pro-Hadi forces.

The rebels, who seized Sanaa in September and have since swept across many other regions, bombed a village south of Taiz, killing 14 civilians, a local official said.

Sporadic clashes also continued in Aden, the scene of fierce fighting since rebels advanced on the southern port in late March after Hadi took refuge there.

Aden health chief al-Khader Laswar said four people were killed in clashes Sunday and 39 were wounded, among them two children and four women.

Laswar has said that 517 civilians and pro-Hadi fighters have been killed there in the past 50 days. The toll includes 76 women and children, he said.

Quoted by the government news agency Sabanew.net, Laswar said he could not provide a toll for the rebels.

He added that 3,461 people were wounded, and said most Aden hospitals were currently out of service as “most” medics have fled.

The United Nations has expressed deep concern about the civilian death toll from the bombing as well as the humanitarian impact of an air and sea blockade imposed by the coalition.

It says more than 1,600 people have died in the conflict since late March. Al Jazeera