Emirati-backed separatists seeking to revive the formerly independent state of South Yemen have in recent weeks made territorial gains, while regional heavyweight Saudi Arabia has warned them to pull back.

There were no immediate reports of casualties in the air strikes, which came amid a dramatic escalation in a conflict that, for more than a decade, has plunged Yemen into humanitarian catastrophe.

Recent separatist advances have added pressure on ties between regional powers Saudi Arabia and the UAE, which support rival groups within Yemen's internationally-recognised government.

On Friday, following a Saudi call on them to pull back, the separatists accused Riyadh of conducting air strikes on their positions.

A video aired on separatist-affiliated media showed a plume of smoke rising from the desert, with four-wheel white cars in the foreground.

"The Council affirms that such actions will not serve any path of understanding and will not deter the people of the South from continuing to move forward toward restoring their full rights," the separatist Southern Transitional Council (STC) said.

The Saudi-led coalition, which backs the government, did not immediately respond to AFP's request to confirm the strikes.

- 'Last resort' -

A Yemeni government official in Riyadh told AFP earlier this week that Saudi Arabia was considering military action against the STC as a "last resort" should efforts to persuade the group to withdraw from newly-seized territory fail.

The head of Yemen's presidential council Rashad al-Alimi met with Western ambassadors and with Saudi Arabia's defence minister and dispatched government envoys to Aden to persuade the STC to withdraw from Hadramawt and Mahra, said the official, requesting anonymity to discuss sensitive matters.

Earlier this month, a Saudi-Emirati military delegation visited Aden to ask the STC to return the two provinces, with Saudi deescalation efforts still ongoing, Riyadh said on Friday.

If efforts to return those areas collapse, Saudi Arabia had signalled to the Yemeni government that it could launch air strikes and deploy the so-called Nation Shield forces, a Salafist group it backs, to advance on the ground.

The air strikes followed clashes in the area on Thursday between the separatists and a tribal leader close to Saudi Arabia, which killed two separatist fighters according to the STC.

A separatist military official in Hadramawt told AFP that the tribal leader had left the country after the fighting.

The strikes also came a day after Saudi Arabia urged the separatists to withdraw from Hadramawt and Mahra provinces.

On Friday, the UAE welcomed efforts by Saudi Arabia to support security in Yemen, as the two Gulf allies sought to present a united front despite backing different sides in the fighting.

Oman, a mediator that also borders Yemen, called for "avoiding escalation... and engaging in a comprehensive political dialogue".

- 'Serious ramifications' -

UN Secretary-General Antonio Guterres warned last week that the STC's advances raised the risk of "wider escalation and further fragmentation".

"A full resumption of hostilities could have serious ramifications on regional peace and security," he said, urging parties to deescalate.

Yemen has been divided by conflict for more than a decade.

The Houthis pushed the government out of the capital Sanaa in 2014 and went on to secure control over most of the north, which includes the country's major population centres.

The Iran-backed Houthis have been at war with the government, backed by a Saudi-led coalition since 2015, in a conflict that has killed hundreds of thousands of Yemenis and triggered a major humanitarian crisis.

Fighting, however, had decreased significantly since a UN-negotiated truce in 2022.

strs-aya/ser