(Recasts with Westerners flown to Oman)
By Mohammed Ghobari
DUBAI, Sept 20 (Reuters) - Yemen's Houthis flew two U.S. citizens and one Briton they held for several months to Oman on Sunday, sources in the group said, in what appears as a goodwill gesture ahead of talks with the United Nations on efforts to end nearly six months of fighting.
The three Westerners had been held by the Houthis since the early days of a Saudi-led military campaign in March on charges of entering the country without proper visas.
The source said the three accompanied a delegation of the Houthi group on an Omani flight to Muscat, where they were due to meet U.N. special envoy to Yemen, Ismail Ould Cheikh Ahmed, for talks on efforts to push a peace deal in the country.
The Houthis were expected to hand over the three Westerners, including a Briton of Yemeni origin, to Omani authorities who would arrange their return to their governments, but the source did not give any details.
The Houthi source said the Briton had been studying at a religious school in Yemen, but it was not clear what the U.S. citizens were doing.
Oman, a member of the six-nation Gulf Cooperation Council that also includes Saudi Arabia, Qatar, Bahrain, Kuwait and the United Arab Emirates, has largely remained neutral in the conflict over Yemen, hosting talks to try to resolve the crisis peacefully.
Oman had previously used its good relations with Yemen's Houthis and Iran to free westerners in the past.
A Saudi-led coalition intervened militarily in Yemen in March to shore up President Abd-Rabbu Mansour Hadi after the Houthis, backed by supporters of former President Ali Abdullah Saleh, launched a push against his southern stronghold in Aden.
More than 4,500 people have been killed in the fighting since March, according to United Nations figures.
On Saturday, Oman said it had summoned the Saudi ambassador to Muscat to file an official complaint over what it said was the targeting of the residence of its ambassador in Sanaa during strikes on the capital on Friday night.
The Saudi-led coalition spokesman has denied the accusation and suggested that the ambassador's residence may have been hit by mortars, possibly fired by the Houthis, the Saudi-owned Asharq al-Awsat newspaper said on Sunday.
Asharq al-Awsat quoted Brigadier-General Ahmed al-Asiri as saying the coalition would welcome an investigation and suggested the house may have been hit by a Houthi mortar shell.
"One would be able from the beginning to distinguish between a mortar strike and a plane strike," he said.
Coalition air raids have intensified in recent weeks as a Gulf Arab ground force and fighters loyal to Hadi prepare a campaign to recapture Sanaa, seized by Houthi fighters in September 2014.
Residents said about 10 air strikes were launched on the Interior Ministry building in the north of the capital, a police camp close to it and a military building.
The Houthi-run Saba news agency said on Sunday the total of people killed in Saturday's air strikes had risen to 40 with 130 more injured, and prompted the health ministry to issue an urgent appeal for medical supplies.
Sanaa residents on Sunday reported a calm night, but local officials in the central province of Ibb said 10 people were killed and 15 others injured there in air strikes targeting a government compound dedicated to fighting al Qaeda.
The coalition sees the Houthis as proxies for non-Arab Iran, which they accuse of trying to expand its influence into Saudi Arabia's Arab neighbours. Iran denies those allegations. (Reporting by Mohammed Ghobari in Sanaa and Marwa Al-Malik in dubai, writing by Sami Aboudi, editing by Tom Heneghan and Clelia Oziel)
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