Saudi Arabia has announced a slew of development projects across southern Yemen worth about $500 million, many in areas long-held by the United Arab Emirates and allied separatists who were routed in a Saudi-backed offensive this month.

The move signals an increasingly assertive posture by the Gulf Arab kingdom in Yemen in a row with the UAE. The separatist Southern Transitional Council swept through parts of the south last year and advanced to within reach of the Saudi border. Riyadh declared the move a threat to its national security, called on the UAE to withdraw and backed an offensive that swept the STC from power.

On Wednesday, Saudi Defence Minister Khalid bin Salman met with the head of the internationally recognized government and several members of the country's Presidential Leadership Council to affirm the kingdom's support, according to a post on his official account on X.

The same post announced aid and projects across 10 provinces, including the construction of hospitals, schools and roads and the donation of fuel to increase power production.

It also announced the construction of a mosque on the island of Socotra named "The Custodian of the Two Holy Mosques", a reference to the official title of the Saudi king. The strategic island had been held by the UAE for years until recently.

"This support embodies the kingdom's keenness to enhance security and stability, and to contribute to building a better future for Yemen and its brotherly people," the post said.

Saudi Arabia and the UAE previously worked together in a coalition battling the Iran-backed Houthis in Yemen's civil war, which caused one of the world's worst humanitarian crises.

But the two most powerful countries in the Gulf have sharp differences over a wide range of issues across the Middle East - from geopolitics to oil output - and those with the STC advance.