An American among several believed to be held by Iran-backed Houthis in war-ravaged Yemen was on Monday freed and flown to neighboring Oman, which is hosting talks between the US and the rebels.
A diplomat in Oman said the "secret" talks between the Americans and the Houthis were to promote peace negotiations, which the UN has so far failed to organize in Geneva.
The news of the American's release, which was confirmed by a US State Department official, came as Omani state media reported that a Singaporean had also arrived in the sultanate before they both return home.
The official ONA news agency said the pair had been "found" with help from Muscat which had "coordinated with concerned parties in Yemen to search for the American citizen and the Singaporean."
The US official said, "I can confirm that a formally detained US citizen has departed Yemen and is currently in Muscat, Oman."
There was no confirmation of the man's identity, where he had been held or by whom.
He was met by the US ambassador, the official said.
The State Department said on Sunday it was working to secure the release of "several US citizens" held in Yemen, where fighting has raged for months amid an insurgency by the Shiite rebels.
The Washington Post for its part reported that the Americans were believed to be held by the Houthi militia in a prison near the rebel-controlled capital Sanaa.
One of the prisoners had been approved to be released in recent days, but the rebels went back on their decision, the Post said.
He had initially been detained for overstaying his visa, but then the rebels accused him of travelling to "sensitive" areas in Yemen.
Saudi Arabia is leading an Arab coalition that launched an air war on the Houthi rebels and their allies in Yemen since March 26.
Diplomatic sources in Oman said on Monday that talks were ongoing between a US delegation and Yemen's Shiite rebels.
"During these secret and informal talks, the Americans are seeking to bring closer positions of the Houthis on one hand, and the Saudis and President [Abed Rabbo Mansour] Hadi on the other, with the hope of convincing these to lower the cieling of their demands," one diplomat said.
The Geneva conference had been due to take place on May 28 but was postponed, in a blow to UN efforts to end a conflict estimated to have killed almost 2,000 people.
Yemen's government says it will only take part once rebels withdrew from at least part of the territory they have seized, in line with a UN Security Council resolution.
In Riyadh, UN special envoy Ismail Ould Cheikh Ahmed arrived from weekend talks in Sanaa and met with exiled Hadi.
Iran is accused of arming the Houthi rebels, a claim the Shiite-dominated country denies.
Yemen's neighbor Oman has good ties with both Tehran and Riyadh, and Muscat has often played the role of mediator.
It is the only member of the six-nation Gulf Cooperation Council not to have joined the Saudi-led coalition.
In the Yemeni capital, at least eight civilians were killed and 20 wounded in explosions sparked by coalition raids on rebel arms depots, a medical official said.
The strikes on Mount Noqum base in eastern Sanaa sent munitions and shrapnel flying into adjacent residential neighborhoods, witnesses said.
Other strikes hit rebel positions in Amran, north of Sanaa, Taez farther south, Marib in the east, as well as arms depots in western Hodeidah province, residents said.
Coalition warplanes struck other rebel positions in the southern province of Daleh, military and tribal sources said.
In Abyan province, also in the south, at least 20 rebels were killed in an ambush that targeted one of their convoys, an official said.
Clashes in Yemen's second city Aden left dead more than eight people, including three civilians, and 133 wounded in the past 48 hours, medics said.
A UN-chartered ship loaded with humanitarian supplies bound for Yemen was targeted by shelling as it approached Aden on Sunday, a provincial government official said, blaming the Houthis.
The World Food Programme confirmed the ship was diverted to the port of Hodeidah farther north.
Meanwhile, the captors of Frenchwoman Isabelle Prime, kidnapped in Yemen on February 24, have posted the first video of her since her abduction, in which she appealed to the French and Yemeni presidents to take action to secure her release.