Rebel fire on a residential district of Yemen's second city Aden killed at least 31 civilians Wednesday as loyalist forces in the central city of Taez launched a manhunt for 1,200 escaped prisoners.
Both cities have seen heavy fighting as loyalists of exiled President Abedrabbo Mansour Hadi battle to fight back Shiite Huthi rebels with the support of a Saudi-led bombing campaign launched in March.
Aden was Hadi's last refuge before he fled into exile in neighbouring Saudi Arabia in March and his supporters have been battling to defend it against the rebels and renegade troops.
The Huthis and their allies pounded the loyalist-held Al-Mansura district with 15 Katyusha rockets, loyalist forces spokesman Ali al-Ahmadi said.
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, he told AFP.
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.
The city's health chief Al-Khader Laswar said more than 100 people were wounded, and that three women and two children were among the dead.
Civilians were seen carrying bloodied bodies and calling for help as they piled them into vehicles and drove them to hospitals.
Overnight, rebel positions in the nearby neighbourhoods of Dar Saad and Khor Maksar had been hit by a series of Saudi-led air strikes, said residents.
A coalition strike in neighbouring Lahj province killed 13 rebels, an official said.
On Monday, United Nations Secretary-General Ban Ki-moon called for an investigation after air strikes hit the UN Development Programme compound in Aden, wounding a guard and causing serious damage.
On Tuesday, Human Rights Watch said strikes on the rebel stronghold of Saada in Yemen's northern mountains had destroyed houses, markets and a school, in what could amount to war crimes.
In the Saudi Red sea city Jeddah, Yemen's exiled Prime Minister Khaled Bahah accused the rebels of committing a "war crime" in Aden by attacking residential areas, laying siege on the city, and forcing aid vessels to turn back.
Hadi had "sent an official letter" to Ban urging the international community to "carry out its duties, beyond just condemnations," Bahah told reporters.
Also in Saudi Arabia, the official SPA news agency reported late Tuesday that the coalition announced the death of a soldier "as result of injuries he suffered from yesterday (Monday) while carrying out his duties" in the Najran area, bordering Yemen.
At least 45 people, civilians and troops, have now lost their lives in shelling and skirmishes along the Saudi side of the border since the air campaign on Yemen's rebels began.
- Qaeda members escape -
In Taez, Yemen's third biggest city, loyalist forces were searching for 1,200 inmates, including Al-Qaeda members, who made a mass breakout as the prison was captured from rebel forces.
A loyalist source accused the rebels of deliberately throwing open the gates in an apparent attempt to cover their withdrawal.
"Between five and eight Al-Qaeda members were among the prisoners," a military source said.
There have been repeated jailbreaks in Yemen since the Huthi launched an offensive last summer, overrunning the capital and then much of the rest of the country.
Al-Qaeda's Yemen arm took advantage of the rebellion to seize the southeastern port city of Mukalla in April where it freed more than 300 inmates, including one of its leaders.
Washington regards Al-Qaeda in the Arabian Peninsula as the network's most dangerous branch and has kept up a drone war against its leaders.
But the Islamic State group too has exploited the conflict to enter the fray, carrying out a string of deadly attacks against Shiite targets since March.
An attack claimed by the Sunni extremists on Huthi leaders in the rebel-held capital Sanaa killed at least 28 people on Monday.
The United Nations has called repeatedly for a humanitarian ceasefire to allow the delivery of desperately needed relief supplies.
UN envoy Ismail Ould Cheikh Ahmed renewed the appeal in talks with Hadi in the Saudi capital late on Tuesday, a government official said.
"The government is coming under pressure from the United Nations for a truce," the official said.