Fighting between Yemeni government forces and separatists in the southern port city of Aden has continued for a third consecutive day, with reports of at least 20 people killed.
The violence in the seat of Yemen's internationally-recognised government threatens to open a new front in the country's devastating war, exposing a rift in a Saudi-led military alliance that has been battling the Houthi rebel movement since 2015.
At least five civilians were among the dead and dozens were wounded in Friday's violence, according to doctors and security officials who spoke to news agencies and other reporters on the condition of anonymity.
Much of the fighting between forces loyal to President Abd-Rabbu Mansour Hadi and a United Arab Emirates-backed militia is taking place in areas that are among the city's most populated, leading to serious concerns for the safety of civilians.
"Many appeals have been issued by civilians who are suffering from chronic diseases because the situation is getting dangerous for them to stay trapped between both fighting sides," said Al Jazeera's Mohammed al-Attab, reporting from Yemen's Houthi-held capital, Sanaa.
In a statement published on Friday, the Norwegian Refugee Council (NRC) expressed deep concern for the safety of its staff and civilians, who have been trapped inside their homes since the fighting began on Wednesday, especially in Aden's Crater neighbourhood.
"NRC currently has nine Yemeni staff members who are trapped by the fighting in the Crater area. We are extremely worried about their safety and well-being," said Mohammed Abdi, the organisation's country director in Yemen.
"There has been heavy, continuous shelling. We're still hearing clashes in my neighbourhood," Amgad, an NRC staff member in Yemen, said.
"The water supply has stopped for days. People have small water tanks with enough water to last for one or two day’s maximum. There isn’t enough water and this is one of the main concerns," Amgad added.
'Not getting along for months'
Now in its fifth year, Yemen's war between the Houthis and the coalition-backed, pro-government forces has claimed tens of thousands of lives and thrust millions to the brink of famine, in what the United Nations has called the worst humanitarian crisis in the world.
The clashes that began on Wednesday in Aden have pitted Hadi's guards against a militia known as the Security Belt. Hani Bin Braik, deputy head of the so-called Southern Transitional Council, had called upon separatists to march to the presidential palace, which is largely empty since Hadi is based in Saudi Arabia.
The government, in turn, has accused the separatist leader of fomenting sedition that would only serve the rebels and called upon the governments of Saudi Arabia and the UAE to press the separatists to halt their attacks.
"They are on the same side in terms of fighting the Houthis ... however, in reality they have not been getting along for months," Sama'a al-Hamdani, of the Middle East Institute, told Al Jazeera from Washington, DC.
"Southern separatist forces, especially those represented in the Southern Transition Council, have called repeatedly for secession, and feel like the time is ideal to self-determination and to pursue it now," al-Hamdani added.
"It seems that although they are fighting against a common enemy, the time has come where differences among them are more important than fighting that enemy."
The International Crisis Group warned on Friday that the fighting would "make an already multi-faceted conflict even more complex and intractable".
"Such a conflict would deepen what is already the world's worst humanitarian crisis and make a national political settlement harder to achieve," read a statement issued by the Brussels-based group.
Stephane Dujarric, spokesman for the UN chief, also raised concerns over the fighting and called on the different sides to "recommit themselves to a political process".
Resumption of food aid
While fighting gripped Aden for a third straight day, The World Food Program (WFP) announced on Friday that it would resume food aid in the Houthi-controlled Sanaa after the end of the upcoming Muslim holiday of Eid al-Adha.
In a move that affected 850,000 people, the WFP announced in June it was partially suspending its aid to the capital amid accusations that the Houthis were diverting the food from the some of the worst affected people in the war-torn country.
The WFP did not elaborate on the details of the agreement, saying only that it had reached a deal with the rebels in regards to the resumption of aid distribution.
According to the WFP, rebel authorities granted the organisation "written guarantees" that it can bring in all staff and equipment needed, and would be given "unimpeded access" to all areas where it needs to work.