By mohammed mukhashaf
ADEN (Reuters) - Saudi-backed Yemeni militiamen captured Aden's main port and a neighboring district on Wednesday, a big prize in their battle to drive Houthi forces from the southern city, residents and fighters said.
Coming a day after the fighters wrested the city's airport and another district from the Houthis, the advance has dealt the biggest setback yet to the Iran-allied Houthis in more than three months of war.
Houthi forces withdrew from the port and Mualla district into Tawahi and were slowing the militiamen's advance in another area called Crater, using intense sniper fire from volcanic crags which overlook the seaside metropolis.
Medics said dozens of combatants and civilians had been killed in the last two days of fighting and the main hospital made an urgent appeal for blood donations.
Saudi Arabia and other Arab states have been bombing the Houthis and their allies from the air since March 26 in the hope of reinstating Yemen's President Abd-Rabbu Mansour Hadi, an ally of Saudi Arabia who fled into exile in Riyadh.
The Houthis say their takeover of the capital Sanaa in September and armed push into Yemen's south and east in March and April are part of a revolution against a corrupt government and hardline Sunni Muslim militants.
Residents said scores of southern fighters were in the streets of Aden fighting on Wednesday as part of the offensive dubbed "Operation Golden Arrow".
A Reuters witness saw about 40 armored vehicles, which the militiamen said were provided by the United Arab Emirates (UAE) and were vital for their battle to win back control of the airport.
Residents said scores of fighters amassed at the entrance of Mualla in the morning and heavy exchanges of gunfire erupted with Houthi forces, who were pushed over the course of several hours into Tawahi district.
A struggle for power in Yemen exploded into an international crisis in late March when the Houthis entered Aden - the country's main port and second city - and a Saudi-led coalition began its air campaign.
Pitting mostly Sunni Muslim fighters in Yemen's south against the Shi'ite Houthis, the war is tinged with some of the sectarian and regional rivalries defining other wars in the region.
The combat looks set to simmer despite a deal reached by world powers and Iran over its disputed nuclear program on Tuesday.
Riyadh, waging a regional struggle for influence with Iran, reacted warily to the deal, saying it would make the Middle East more dangerous if it conceded too much to Tehran.
Ali al-Ahmedi, spokesman for anti-Houthi forces in the city, said earlier on Wednesday that they would build on their capture on Tuesday of Khormaksar - an area that acts as a bridge between the mainland and a peninsula where much of the city lies.
"The southern resistance in coordination with reconstituted army units and coalition aircraft are moving into position to lift the siege on the area of Crater, Mualla and Tawahi and to storm and seize them back," al-Ahmedi said.
"The clearing of these areas is a matter of hours," he said.
Pro-Houthi media said the air campaign continued unabated on Wednesday, killing 13 people in bombings throughout the country.
Following Tuesday's advance, residents of cities across Yemen's south set off fireworks, honked horns and chanted slogans promising a swift victory over the Houthis.
The country's proximity to Saudi Arabia, the world's top oil exporter, makes the instability a cause for international concern.
Yemen has also been in the frontline of the United States' global war against Islamist militants but American personnel pulled out of the country as the internal conflict worsened.
The fighting in Aden has taken a dreadful humanitarian toll, with flood, medicine and other necessities in short supply. A U.N.-brokered ceasefire to allow delivery of aid collapsed within days.
More than 3,000 people have been killed and more than one million displaced since the conflict broke out.
(Writing by Noah Browning, Editing by William Maclean and Angus MacSwan)