"The Yemeni government condemns the Emirati air strikes against government forces in the interim capital Aden and in Zinjibar, which resulted in civilian and military casualties," Deputy Foreign Minister Mohammad al-Hadhrami said in a tweet.

The UAE has trained and supported separatists who seek an independent southern Yemen, although it is a key pillar in a Saudi-led coalition backing the Yemeni government against Iran-aligned Huthi rebels.

Hadhrami urged Saudi Arabia "to stand by the legitimate government and stop this illegal and unjustified military escalation".

The deputy foreign minister did not say when the alleged air strikes took place.

But residents in Aden told AFP they heard air strikes late Wednesday when forces loyal to Yemeni President Abedrabbo Mansour Hadi entered Aden.

The UAE-backed Security Belt force -- dominated by the separatist Southern Transitional Council (STC) -- regained full control of Aden on Thursday, according to an STC spokesman Haitham Nezar.

A government security source confirmed Aden was under the full control of the STC, saying government troops who entered parts of the city a day earlier "withdrew from Aden" to Abyan province.

Separatists captured the strategic city on August 10 after a fierce battle that left at least 40 people dead.

The Yemeni government has accused the UAE of supporting the "coup" in Aden.