Yemeni troops have taken part in a raid to rescue a group of eight hostages being held by al-Qaeda, in which seven militants were reportedly killed.
One soldier was injured during the operation in the eastern province of Hadramawt, Yemeni officials said.
Six Yemenis, a Saudi and an Ethiopian were freed. The US denied reports of an American hostage being rescued.
There were also conflicting reports about whether US special forces took part in the rescue.
The Yemeni Supreme Security Committee's statement made no mention of any US involvement on the ground, but the New York Times said about two dozen American commandos had led the raid.
Citing officials from both countries, the newspaper reported that they and a small number of Yemeni counter-terrorism troops had flown by helicopter near to a cave in the remote Hajr al-Sayar district of Hadramawt where the hostages were being held.
The troops then hiked some distance in the night to the cave, where they surprised the militants from al-Qaeda in the Arabian Peninsula (AQAP), the New York Times said.
Seven militants were killed in the ensuing firefight, it added. The hostages were not harmed and were evacuated by helicopter.
The US defence department referred questions about the raid to the Yemeni government.
The Supreme Security Committee said one of those freed was Khalil al-Mekhlafi, who was kidnapped in the southern province of Bayda in June 2013.
Mr Mekhlafi was working as a lecturer at al-Bayda University at the time, having previously served as a police officer, and was reportedly seized along with two of his colleagues.
It is not clear if the freed Saudi national is Abdullah al-Khalidi, the kingdom's deputy consul in the southern port city of Aden, who was abducted in March 2012.
Mr Khalidi appeared in a video in September 2014 in which he appealed to the Saudi government to negotiate his release. AQAP militants said they were holding him in a bid to secure the release of female prisoners in Saudi Arabia and to raise a ransom.
AQAP is also believed to be holding a South African teacher kidnapped in May 2013 and an Iranian embassy official who went missing in July 2013.