Authorities in five southern provinces in Yemen have rejected a separatist group’s claim to self-rule, further heightening tensions among ostensible allies in the Saudi-led coalition battling Houthi rebels elsewhere in the country.

The separatists’ Southern Transitional Council (STC), which is backed by the United Arab Emirates, scrapped a peace deal with the Saudi-backed government of President Abd-Rabbu Mansour Hadi and declared a state of emergency overnight.

The separatists said they would “self-govern” the key southern port city of Aden and other southern provinces, accusing the government of corruption and mismanagement.

The STC seeks the return of the independent state that existed in the south until 1990.

Yemen’s internationally recognised government rejected the STC’s self-governance, and described the move as a continuation of the armed rebellion that started last August.

The government said local and security authorities in the provinces of Hadramout, Abyan, Shabwa, al-Mahra and the remote island of Socotra dismissed the move as a “clear and definite coup”.

Some of the provinces issued their own statements condemning it.

The authority to declare an emergency lies with the president only, and militias cannot replace state institutions, Shabwa security forces said in a written statement.

The administration of Hadramout, the biggest province in the south, said the STC’s announcement is “a violation of legitimacy and the Riyadh Agreement”, referring to a 2019 power-sharing deal between the separatists and the Yemeni government.

Abyan and Socotra administrations called for loyalty to the president, while the local authorities of al-Mahra province said the STC’s step aimed to deepen the crisis already existing in the country.

The STC did not immediately comment on the statements from the five provinces.

Saudis ‘caught in the middle’

In August, STC-aligned forces seized control of Aden, the temporary seat of Hadi’s government. The STC and the Yemeni government later agreed on a power-sharing deal. Brokered by Saudi Arabia, the agreement included arrangements for a government reshuffle and for military and security forces to be incorporated into the defence and interior ministries, although it has not been fully implemented.

Peter Salisbury, a Yemen expert at the Brussels-based International Crisis Group think tank, said tensions between Hadi’s government and the separatists have been rising for months.

He said both sides have exchanged accusations of noncompliance with the peace deal, and were building up forces with intent to resume infighting.

He said Saudi Arabia, which brokered the power-sharing deal and had been overseeing its implementation, was expected to intervene.

“Each side wants the Saudis to support its narrative and Riyadh is really caught in the middle right now,” Salisbury said.

Catherine Shakdam, head of the Yemen department at the London-based Next Century Foundation, a peacebuilding think tank, told Al Jazeera that the main issue for Saudi Arabia has to do with the fact that it has backed the Hadi government.

“Hadi has lost whatever legitimacy he may have had at some point. We need to remember that the only legitimacy that he had was, in fact, given by the international community,” Shakdam said.

“There was an understanding that if he wasn’t supported by the international community, then de facto sovereignty would fall onto the Houthi movement,” she added.

Yemen’s civil war began in 2014 when the Houthis took control of the country’s north, including the capital, Sanaa, and drove Hadi from power.

A Saudi-led military coalition intervened against the rebels in an attempt to restore the government the following year.

The conflict has killed more than 100,000 people and created the world’s worst humanitarian crisis, leaving millions suffering from food and medical shortages.