Defiant Shi’ite militiamen have seized control of Yemen’s presidential palace and attacked President Abdrabuh Mansur Hadi’s residence in an apparent bid to overthrow the embattled government, drawing condemnation from the UN Security Council.

The council backed Hadi as “the legitimate authority” and called on all parties and political actors in Yemen to stand with the government “to keep the country on track to stability and security”.

Abdul Malik al-Huthi, leader of the militia which overran the capital Sanaa in September, was defiant, warning that “all options” were open against Hadi, whom he accused of supporting the “fragmentation” of the country.

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After a lull in violence overnight, Huthi gunmen seized the palace and attacked Hadi’s Sanaa residence, with the president reportedly inside, shattering a brief ceasefire.

Escalating violence in the capital in recent days has raised fears that Hadi, a key US ally in its fight against al-Qaeda, will fall and the country descend into chaos.

Tensions have been running high since Saturday, when the Huthis abducted Hadi’s chief of staff, Ahmed Awad bin Mubarak, in an apparent move to extract changes to a draft constitution opposed by the militia.

Information Minister Nadia Sakkaf said the militia had attacked Hadi’s residence in western Sanaa on Tuesday, after witnesses reported clashes in the area.

Hadi was earlier reported to have been in the building meeting with advisers and security officials.

“The Yemeni president is under attack by militiamen who want to overthrow the regime,” Sakkaf said on Twitter.

Witnesses said the fighting outside the residence appeared to have subsided after two soldiers were killed.

A military official said the militiamen had also seized the presidential palace in southern Sanaa, where Hadi’s offices are located, and were “looting its arms depots”.

Prominent Huthi member Ali al-Bukhaiti said on Facebook that the fighters had “taken control of the presidential complex”.

Authorities in Yemen’s second city Aden shut its international airport on Wednesday in protest against attacks by the Huthis on the president and other state figures.

Aden’s main security body said in a statement that it was closing its airport, its seaport and entrances to the city because of “dangerous developments in the capital” and “attacks on the symbol of national sovereignty and constitutional legitimacy, President Abdrabuh Mansur Hadi”.

“We hold the Huthis responsible for the safety of all symbols of constitutional legitimacy,” the statement said, naming Hadi, Bahah and Mubarak.

As the UN Security Council began its emergency meeting, Secretary-General Ban Ki-moon said he was “gravely concerned” and called for an immediate halt to the fighting.

UN special envoy Jamal Benomar told the council via videolink that the Huthi fighters had launched a “massive attack using heavy weapons” on the palace, a diplomat present at the closed meeting said.

EU foreign policy chief Federica Mogherini said “all parties must step back immediately from conflict”.

But Huthi said “all options are open in this action” and that “no one, the president or anyone else, will be above our measures if they stand to implement a conspiracy against this country”.

In a long televised address, he also warned the Security Council that “you will not benefit from any measures you wish to take” against the Huthis.

“We are ready to face the consequences, regardless of what they are,” he said.

The council did not threaten any sanctions although it called for a full ceasefire and a return to dialogue, .

The fresh unrest shattered the ceasefire agreed after a bloody Monday that saw the Huthis, who bear the name of their leader’s late father, tighten their grip on the capital.

– AAP