The United Arab Emirates said on Tuesday it was pulling its remaining forces out of Yemen after Saudi Arabia backed a call for UAE forces to leave within 24 hours, deepening a crisis between the two Gulf powers and oil producers.

Hours earlier, Saudi-led coalition forces had attacked the southern Yemeni port of Mukalla. The airstrike on what Riyadh said was a UAE-linked weapons shipment was the most significant escalation to date in a widening rift between the two Gulf monarchies.

In Washington, the US State Department said Secretary of State Marco Rubio spoke with the Saudi and UAE foreign ministers about tensions in Yemen and other issues affecting security in the Middle East.

Several Gulf countries, including Kuwait and Bahrain, said they would support any efforts to bolster dialogue and reach a political solution. Qatar said the security of Saudi Arabia and other Gulf countries "constitutes an inseparable part" of its own security.

Once the twin pillars of regional security, the Gulf heavyweights have seen their interests diverge on everything from oil quotas to geopolitical influence.

The UAE defence ministry said it had voluntarily ended the mission of its counterterrorism units in Yemen, its only forces still there after it concluded its military presence in 2019.

The ministry said its remaining mission was limited to "specialised personnel as part of counterterrorism efforts, in coordination with relevant international partners".

In a statement, it said recent ⁠developments had prompted a comprehensive assessment, the state news agency WAM reported.

Saudi Arabia had accused the UAE of pressuring Yemen's separatist Southern Transitional Council (STC) to push towards the kingdom's borders, and declared its national security a "red line".

It was Riyadh's strongest language yet in the falling-out between the neighbours, who once cooperated in a coalition against Yemen’s Iran-aligned Houthis but have seen their interests there steadily diverge.

The UAE withdrawal of the few forces it had kept in Yemen may ease tensions for now. But questions remain over whether it will keep supporting the STC.

Riyadh for its part has continued, through the coalition it heads, to back Yemen's internationally recognised government and the cabinet said it hoped the UAE would end all military or financial assistance to the STC.

The coalition bombed what it said was a dock used to provide foreign military support to the separatists.

Rashad al-Alimi, head of Yemen's Saudi-backed presidential council, gave Emirati forces 24 hours to leave.

The UAE said it had been surprised by the airstrike, and that the shipments in question did not contain weapons and were destined for the Emirati forces. But it said it sought a solution "that prevents escalation, based on reliable facts and existing coordination".

Yemen's Saudi-led coalition said a shipment arriving from the United Arab Emirates to Yemen's southern port of Mukalla had containers loaded with weapons and ammunition.

The coalition said it had information that such weapons would be transported and distributed to locations in Yemen's Hadramout.

In a televised speech, Alimi said it had been "definitively confirmed that the United Arab Emirates pressured and directed the STC to undermine and rebel against the authority of the state through military escalation", according to the Yemeni state news agency. (Reuters)