AFP/Aden

Rebel fire on a residential district of Yemen's battleground second city Aden killed at least 20 civilians and wounded 41 early Wednesday, medical sources said.

The Houthi Shia rebels and their allies pounded the city's loyalist-held Al-Mansura district with 15 Katyusha rockets from their positions in the Dar Saad neighbourhood, loyalist forces spokesman Ali al-Ahmadi told AFP.

The rocket fire began before dawn when the streets were busy ahead of the daytime fast observed by Muslims during the holy month of Ramadan, Ahmadi said.

A fresh salvo of rockets later in the morning hit mourners burying some of the dead from the earlier fire, the spokesman and witnesses said.

"Many of the wounded are in serious condition," a medical source told AFP.

Aden was the last refuge of President Abedrabbo Mansour Hadi before he fled into exile in neighbouring Saudi Arabia in March and his loyalists have been battling to defend it against the rebels with the support of Saudi-led air strikes.