By Mohammed Mukhashaf and Amena Bakr
ADEN/DOHA (Reuters) - Saudi-led air strikes hit five Yemeni provinces as fighting raged in the southern city of Aden on Wednesday, and sources in the region said the kingdom was training armed tribesmen to fight the Iran-allied Houthi group.
Houthi rebels' tanks and snipers killed at least 12 civilians overnight in Yemen's Aden as they advanced toward the centre of the city, residents said, and a Saudi-led coalition airdropped arms to anti-Houthi fighters in the city of Taiz.
The Houthis took the capital Sanaa in September, demanding a more inclusive government, and swept south, rattling top world oil exporter Saudi Arabia and its allies, who fear what they see as expanding Iranian influence in the region. Arab coalition air strikes have, over the last month, backed local fighters in Aden and nationwide battling Shi'ite Houthis.
Heavy clashes shook the Khor Maksar district in Aden, seen as the main bulwark against the Houthis, and dozens of families fled the district on Wednesday.
"The world, the coalition and the United Nations need to step in urgently to save our neighbourhood, which has truly become a disaster area after this indiscriminate shelling," resident Ali Mohammed Yahya said.
About 200 km (120 miles) to the north, Arab aircraft dropped weapons for tribal and Islamist militiamen fighting the Houthis in the city of Taiz.
Talks between the Houthis and exiled, Riyadh-based President Abd-Rabbu Mansour Hadi collapsed in early April and he fled. Chaos then set in as the Iran-allied Houthis fought their way south, battling loyalist army units, regional tribes and al Qaeda militants.
Sources in the region told Reuters Saudi Arabia had trained Yemeni armed tribesmen to fight the Houthis, in a sign of its growing involvement in the country's ground war after a month of air operations.
Three hundred tribal fighters trained across Yemen's border with the kingdom were deployed this week back to their home area in the Sirwah district of central Marib province and made gains against the Houthis, a Yemeni official source told Reuters.
"You cannot win a war against the Houthis from the air - you need to send ground forces in, but now there's a programme to train tribal fighters on the border," said a Doha-based military source familiar with the matter.
Despite weeks of bombing, the Houthis have retained their dominant position on battle fronts across Yemen, and no visible progress has been made towards peace talks.
Yemen's government in exile said it would request membership in the Gulf Cooperation Council (GCC), a powerful grouping of Sunni Arab Gulf monarchies, the country's spokesman Rajeh Badi said by telephone from Qatar.
Officials from the Saudi-backed government live mostly in Riyadh and have little influence on the ground in Yemen.
The Arabian peninsula's only republic, Yemen has for decades been at the sidelines of decision-making in the region, but the move may bind its future more closely to its richer neighbours.
Impoverished and strife-torn even before the war, Yemen is now mired in a humanitarian catastrophe, as 300,000 people have been displaced by the conflict and 12 million are short of food.
The World Health Organization said on Tuesday 1,244 people were reported killed and 5,044 wounded in Yemen in the month up to Wednesday.
(Reporting by Mohammed Mukhashaf, Mohammed Ghobari, and Amena Bakr; Writing by Noah Browning; Editing by Ralph Boulton)