Abu Dhabi's crown prince has visited Saudi Arabia and called warring parties in Aden, the temporary seat of Yemen's government, to engage in dialogue to "defuse tensions".
Sheikh Mohammed bin Zayed Al Nahyan's visit on Monday came after United Arab Emirates-backed separatists announced they had effectively taken control of the southern port city following days of clashes with forces loyal to the internationally-backed government of President Abd-Rabbu Mansour Hadi.
The fighting in Aden between the Security Belt - a grouping aligned with the UAE-backed Southern Transitional Council (STC), which seeks the secession of the country's south - and the presidential guards exposed rifts within a Saudi-UAE military coalition that has been supporting Hadi's forces against the Houthi rebel movement in Yemen since 2015.
In a statement carried by Emirates News Agency after his meeting with Saudi Arabia's King Salman bin Abdulaziz, the crown prince "affirmed that the UAE and Saudi Arabia call on conflicting Yemeni parties to prioritise dialogue and reason for the interest of Yemen and its people".
He also said that the two Gulf Arab allies would "adamantly confront any and all powers that threaten the safety and security of the region".
According to the United Nations, the four-day fighting killed up to 40 people and wounded 260 others. But the International Committee for the Red Cross said on Monday that clinics in Aden had reported "scores dead" and hundreds wounded in the fighting, which threatened to open a new front in a long-running conflict that has devastated the Arab world's poorest country.
"Hospitals struggling without basic equipment. Wounded people dying as checkpoints prevent them reaching clinics," the ICRC said in a tweet.
The STC leader Aidarous al-Zubaidi on Sunday said the council was committed to a ceasefire called by Saudi Arabia, adding that he was ready to partake in Saudi-brokered peace talks.
Al-Zubaidi also said the separatists were also willing to work with the Saudi-UAE-led military coalition battling the Houthis, who control vast swaths of Yemen's north, including the capital, Sanaa.
In his speech, al-Zubaidi said last week's violence had been "provoked" by forces loyal to Hadi, who is based in Saudi Arabia's capital, Riyadh.
Separatist fighters were left with "only two options: either self-defence, or surrender and accepting the liquidation of our just cause," Zubaidi said, according to an English translation of his comments posted on the official STC website.
He claimed that loyalist forces wanted "to implement a plan based on the assassination of our leaders, and then to provoke our people and liquidate our presence".
But Yemen's government has accused the STC and the UAE of staging a "coup" against it.
Clashes between the two sides erupted on Wednesday following the funeral of Security Belt members, including a top commander, who were killed in a Houthi-claimed missile attack on August 1 during a military parade in Aden's Buraiqa district.
Hani Bin Braik, the STC's deputy head, accused Hadi's forces of playing a role in the attack and called on the southern separatists to march to the presidential palace and "topple" Hadi's government.
Saudi Arabia called for the ceasefire only after the Security Belt announced its takeover in Aden. Hadi, who met King Salman on Sunday, has yet to comment publicly on the latest developments.
The internationally recognised government's interior minister, however, blamed the presidential office and ally Saudi Arabia for remaining "silent" while acknowledging the UAE's victory in the south.
The UAE, which recently announced the beginning of a troop withdrawal from Yemen, has armed and trained an estimated 90,000 allied fighters in the south.
South Yemen was an independent state until 1990. Strong resentment remains among southerners towards northerners, who they accuse of imposing national unification by force.
The latest events are not the first example of southern separatists opposing forces loyal to Hadi.
In January 2018, clashes between the two sides killed 38 people.