Russia and the Red Cross appealed on Saturday for a military pause in Yemen to allow urgent humanitarian aid deliveries and evacuation of civilians after 10 days of Saudi-led air strikes and fighting in which hundreds of people have died.
Russia distributed a draft resolution at the United Nations pressing for suspensions of the air strikes to allow evacuation of foreign civilians and diplomats, and demanding rapid and unhindered humanitarian access.
The International Committee of the Red Cross called for an immediate pause in hostilities to deliver life-saving medical aid, saying three of its shipments remained blocked.
"All air, land and sea routes must be opened without delay for at least 24 hours to enable help to reach people cut off after more than a week of intense air strikes and fierce ground fighting nationwide," the ICRC said in a statement.
The United Nations says more than 500 people have been killed in the past two weeks in Yemen and nearly 1,700 wounded. Residents in Aden say parts of the southern port city have been without water or electricity for two days.
There was no sign of a halt in the fighting.
Aden residents said ships from the Saudi-led coalition bombarded Houthi forces who have taken over districts close to the center of the city despite Riyadh's military campaign in support of their foe, President Abd-Rabbu Mansour Hadi.
Hadi loyalists managed to push the Houthis and their allies from central Aden's Crater district on Friday, a rare victory after more than a week of gains by the Shi'ite Houthis, who are backed by soldiers loyal to ex-president Ali Abdullah Saleh.
Jets from the Saudi-led coalition parachuted weapons into Aden for a second day to bolster fighters loyal to Hadi, who fled Yemen 10 days ago and has watched from Saudi Arabia as the Houthis advanced on his supporters' last major foothold.
A military spokesman for the Saudi coalition said it was providing substantial logistical support for Hadi's fighters. He declined to confirm or deny reports that Saudi special forces were operating in Aden.
But a fighter in Aden, Khaled Ahmed Saif, appealed on local television for the coalition to send ground troops as soon as possible, saying the city was being subjected to a "genocidal war" by the Houthis.
Late on Saturday, Houthi forces entered the central Aden district of Mualla, where the port is located, and witnesses reported heavy fighting.
Residents said life was becoming unbearable. "How long can people live without water or electricity?" said Mohammad Fara'a. Another Crater resident, Hassan Abdallah, said people were using a long-disused well at one of the mosques to get water.
Near the capital Sanaa, an air strike on the village of Okash killed a family of nine people on Friday night, residents said.
Coalition spokesman Brigadier General Ahmed Asseri, asked about the calls for a humanitarian pause, said only that the military was ready for any instructions from its political leadership. He said aid agencies and governments should coordinate aid shipments with officials in Riyadh.
Tribes against al Qaeda
The conflict in Yemen has turned the impoverished Arabian Peninsula state into the latest theater for Sunni Muslim Saudi Arabia's proxy war with regional Shi'ite rival Iran, a struggle which is also playing out in Syria, Lebanon and Iraq.
Tehran denies Riyadh's charges that its arms the Houthis, who emerged as the country's most powerful faction when they took over the capital six months ago together with supporters of former president Ali Abdullah Saleh.
Saudi Arabia, unnerved by the growing power of the Shi'ite Houthis on its southern flank, launched military attacks on March 26. Saudi jets have been backed by planes from its Gulf Arab neighbors.
The United Arab Emirates state news agency said 100 Saudi aircraft were taking part along with 30 from the UAE, 15 each from Bahrain and Kuwait and 10 from Qatar.
The latest fighting is one of many conflicts in Yemen, where mass demonstrations inspired by the wider Arab uprisings of 2011 led to Saleh's resignation after three decades in power plagued by southern separatism, tribal unrest and al Qaeda militancy.
U.S. military officers conducting a covert drone war against Al Qaeda in the Arabian Peninsula, the group's powerful regional wing, were withdrawn from Yemen last month, and the turmoil may provide the jihadi movement with the chance to entrench or expand in the country's remote east.
Suspected al Qaeda fighters seized the port town of Mukalla on Thursday, freeing scores of prisoners including a local al Qaeda leader and ransacking banks, residents said.
Military sources said they faced relatively little resistance from soldiers in a nearby military base. Soldiers also withdrew from two towns - Shihr and Riyan - further up the Arabian Sea coast, highlighting the further collapse of Yemen's fragile central authority.
On Saturday, armed tribesmen in pickup trucks drove into central Mukalla, about 500 km (300 miles) east of Aden, to expel the al Qaeda militants. They pledged earlier to restore stability in town.