Saudi-led warplanes carried out new strikes against Iran-backed rebels in the Yemeni capital on Tuesday and the UN envoy flew in for talks ahead of a planned five-day humanitarian ceasefire.
The Saudi-proposed truce, due to take effect at 11:00 pm (2000 GMT), aims to allow deliveries of desperately needed relief supplies, although aid groups have already warned that five days are not enough.
The targets of Tuesday's raids included an arms depot in a military base on Mount Noqum in the eastern outskirts of Sanaa, an AFP correspondent said.
It was the second straight day that coalition warplanes had hit the depot, amid intensified attacks on the Shiite Huthi rebels and allied renegade troops loyal to former president Ali Abdullah Saleh.
Twin strikes on Monday killed at least five people and wounded 20, as huge explosions sent debris crashing into a residential area at the foot of the mountain.
The UN says 1,400 people have died in the conflict since late March.
Tensions between Sunni-dominated Saudi Arabia and Shiite Iran have soared following the launch of the aerial campaign on March 26.
Riyadh has repeatedly accused Iran of arming and funding the Huthis, which Tehran denies.
The Huthis have promised to respond "positively" to the planned truce and pro-Saleh troops have accepted the proposed ceasefire.
- 'Dialogue the only way' -
As part of diplomatic efforts to end the bloodshed, the newly appointed UN envoy to Yemen, Ismail Ould Cheikh Ahmed, landed in Sanaa on Tuesday after touring Gulf members of the Saudi-led coalition.
"We are convinced that dialogue is the only way to solve the Yemeni problem," the rebel-controlled Saba news agency quoted him as saying.
The Mauritanian diplomat was appointed late last month following the resignation of his predecessor Jamal Benomar, who lost support from Gulf states.
The ceasefire would be the first since the air war was launched to try to restore the crumbling authority of exiled President Abedrabbo Mansour Hadi.
The truce has strong backing from Washington, which has said it could be extended.
Signup to our newsletter and follow us on Facebook and Twitter!
Riyadh has stressed the offer is conditional on the rebels reciprocating and not exploiting the ceasefire for military advantage.
The United Nations has expressed deep concern about the civilian death toll from the bombing campaign as well as the humanitarian impact of an air and sea blockade imposed by the coalition on Yemen.
- Fighting rages in Aden -
The Huthis, who hail from the mountainous north near the border with Saudi Arabia, overran the capital in September and extended their control to other regions.
Hadi fled to Riyadh as the rebels closed in on his refuge in the main southern city of Aden, where clashes between his opponents and supporters have shown no sign of relenting.
Six people were killed and 53 others were wounded on Monday in fighting in the port city, Aden health authority chief Al-Khader Laswar said. Civilians were among the casualties.
Clashes also raged in the southern city of Daleh and the Abyan provincial capital of Ataq, officials and military source said, reporting that dozens were killed.
AFP could not verify the death tolls.
The Red Cross spokesman in Sanaa, Adnan Hizam, said a humanitarian truce of more than five days was needed.
"We hope the truce would last longer, and become permanent. And we hope all sides respect it," he told AFP, lamenting a "catastrophic" humanitarian situation.
New York-based Human Rights Watch warned that the Huthis had intensified recruitment of children in violation of international law, urging the rebels stop involving minors in the conflict.
Commanders of the rebels and other groups "should stop using children or risk prosecution for war crimes," the rights group said.
HRW said Islamist and tribal militias as well as Al-Qaeda were also recruiting children.
Al-Qaeda has exploited the growing turmoil in Yemen to consolidate its grip on the southeastern province of Hadramawt.
An Al-Qaeda provincial commander was among four militants killed in an apparent US drone attack in Hadramawt on Monday, an official said.
Maamoun Hatem headed Al-Qaeda's forces in the central province of Ibb, the official said.
Washington has waged a longstanding drone war against Al-Qaeda's Yemen branch, which it regards as the most dangerous.