At least 27 people have been killed in clashes in the Yemeni city of Taez .
The clashes were between loyalist forces and rebels as well as Saudi-led coalition air raids.
Residents said the city in southwest Yemen was rocked by explosions and gunfire overnight.
Coalition-backed forces of President Abedrabbo Mansour Hadi battled pro-Iranian Houthi Shia rebels.
Nineteen rebels, four soldiers of a mechanised army unit loyal to the president and four other pro-Hadi fighters were killed, a medical source told AFP.
Yesterday, coalition warplanes carried out heavy air strikes on a presidential palace in Taez, Yemen's third largest city.
They also bombed positions held by special forces units loyal to former president Ali Abdullah Saleh who has sided with the Houthis.
Mr Hadi fled to Saudi Arabia last month as the Houthis closed in on his refuge in the southern city of Aden, having advanced from their stronghold in northern Yemen last year to seize the capital Sanaa.
Residents and security sources said rival fighters clashed last night in districts of Aden.
Pro-Hadi forces with the support of air strikes held off rebels battling for the past week for control of Aden's refinery, 15km to the west of the port city.
Meanwhile, north of Aden, nine rebels were reported killed in two ambushes by pro-Hadi fighters in the north and northwest of Dhaleh city, capital of the province of the same name, a pro-Hadi security spokesman said.