DUBAI: Yemen's internationally recognised government late on Friday rejected "false justifications" from the United Arab Emirates (UAE) for air raids that reportedly killed dozens of government troops in the southern city of Aden.
Abu Dhabi said it launched air raids on Wednesday and Thursday in self-defence against "terrorist militias" threatening a Saudi-led military coalition.
The coalition - in which the UAE is itself a key partner - was formed to combat Huthi rebels in northern Yemen and in support of the government, but Abu Dhabi's commitment to that fighting front sits uneasily alongside its backing of the southern separatists in an increasingly fragmented war.
The UAE's foreign ministry had issued a statement late on Thursday, hours after the separatists regained control of Aden and forced government troops who entered the southern port city a day earlier to withdraw.
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It said the air strikes hit "armed groups affiliated with terrorist organisations", referring to militants it argues make up part of Yemeni government forces.
But Yemen's government hit back on Friday over what it said were "false justifications given by the UAE to cover up its blatant targeting of the national army's forces".
It further accused the UAE of attempting "to attach terrorism to the national army".
In further violence in Aden on Friday, the Islamic State group claimed a suicide bombing that killed three separatist fighters, while a separatist military chief survived a roadside bomb that wounded five of his guards, security sources said.
Security sources had initially blamed both of Friday's attacks on al Qeada, and said separatist forces made several arrests, adding that they aimed to dismantle militant "sleeper cells".
But residents have reported arrests of soldiers loyal to the internationally recognised government.
The separatist Southern Transitional Council alleged Friday's attacks revealed that "terrorists - Deash and al Qaeda - are the other face of this government and its infiltrated institutions".
On August 1, separate attacks in Aden by militants and Huthi rebels killed 49 people, mostly separatist fighters.
The STC accused the government of complicity in those attacks, sparking a showdown between the separatists and the internationally recognised administration.
The intensifying conflict between Abu Dhabi and the government undermines the coalition, and poses a headache for regional powerhouse Saudi Arabia, which remains focused on fighting the Huthis who are aligned with Riyadh's arch foe Iran.
The Yemeni government and separatists have tussled for control of Aden and the neighbouring provinces Abyan and Shabwa over the past three weeks.
Yemen's government had on Thursday already accused the UAE of mounting the air strikes in support of the separatists, in an assault it said killed 40 combatants and wounded 70 civilians.
The UAE, which has a zero tolerance policy towards militants, believes that part of Yemen's army is made up of militants from al Islah, a party considered close to the Islamic Brotherhood.
The allegation was backed by its Yemeni ally, the head of the STC, Aidarus al-Zubaidi, who aims to regain independence for South Yemen, which was forcibly unified with the north in 1990.
At a press conference in Aden on Thursday, he said "internationally wanted terrorists" were among fighters captured during the retaking of the city.
However, Yemeni President Abedrabbo Mansour Hadi redoubled his allegations against the UAE, accusing it late on Thursday of having planned, financed and coordinated attacks on state institutions and military positions in Aden.
The Yemeni head of state, who is in exile in the Saudi capital, called on Riyadh to "intervene to halt the blatant interference of the United Arab Emirates, in support of the militias, and air raids against the armed forces of Yemen".
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The UAE's minister of state for foreign affairs, Anwar Gargash, on Friday urged all sides to go back to the negotiating table under a Saudi proposal for talks in Jeddah.
"The Saudi initiative is the way out of this crisis," Gargash said on Twitter.
Yemen's government has said the STC must first withdraw from its positions.
The coalition intervened in Yemen's war in 2015 in support of the government after the Huthis swept south from their northern stronghold to seize the capital Sanaa and much of Yemen - the Arab world's poorest nation.
The strategic port city of Aden has since then served as the beleaguered government's interim capital.
Fighting over the past four years has already claimed tens of thousands of lives and sparked what the United Nations calls the world's worst humanitarian crisis.