A declaration of self-rule by the most influential Yemeni STC group has triggered concerns that Yemen's conflict could escalate just as the United Nations is seeking a nationwide cease-fire to prevent the spread of the novel coronavirus.

The United Arab Emirates, said Monday that it opposes the declaration and urged the group to honor a peace deal it signed last year with the internationally recognized government affirming shared control of the south. Saudi Arabia — which, along with the UAE, leads a regional Sunni Muslim coalition fighting in Yemen — called for the separatists to reverse their move, describing it as “an escalatory action.”

The United Nations also voiced concern, urging the feuding sides to adhere to the peace deal, known as the Riyadh Agreement. Accusations of delays in implementing the truce appear to have prompted the Southern Transitional Council’s decision over the weekend to declare self-rule.

The tensions were the latest jolt to Yemen’s south, after at least 14 people, including five children, were killed in flash floods last week in the Red Sea city of Aden, the temporary capital of the internationally recognized Yemeni government. The country, the Arab world’s poorest, is already in the grip of the world’s most severe humanitarian crisis after more than five years of conflict. This month the first case of covid-19, the disease caused by the novel coronavirus, was detected, sparking fears that the disease could quickly spread at a time when Yemen is facing deep cuts in humanitarian aid funding.

“The latest turn of events is disappointing, especially as the city of Aden and other areas in the south have yet to recover from flooding and are facing the risk of COVID-19,” Martin Griffiths, the U.N. special envoy for Yemen, said in a statement. “Now, more than ever, all political actors must cooperate in good faith, refrain from taking escalatory actions, and put the interests of Yemenis first.”

The fresh animosities are a reminder of the multiple wars suffocating Yemen. While the primary, and best-known, conflict pits the Saudi-led coalition against northern rebels known as Houthis, the battle for the strategic port city of Aden and other areas in the south involves two allies within the coalition.