By Michael Hernandez

WASHINGTON

America's top diplomat on Sunday welcomed the release of an American citizen who was held in rebel-controlled Yemen.

John Kerry said in a statement the State Department had been working alongside regional partners on the release of Wallead Yusuf Pitts Luqman "since the beginning".

He thanked Sultan Qaboos bin Said Al Said of Oman and his government "for their leadership and assistance in securing Mr. Luqman's safe return," and recognized the "positive gesture" from Houthi rebels.

"The protection of U.S. citizens around the world is among the highest priorities of the Department of State, and today's release is testament to the diligence and seriousness with which we all pursue that goal," he said. "We will be relentless in our efforts to secure the release of Americans unjustly detained overseas, and we continue to call for the release of individuals unjustly held in Yemen."‎

It was not immediately clear how long Luqman had been in captivity, or why he was initially detained.

Oman had previously worked to secure the release of two Americans from Yemen last month.

The country has been a critical player in the region, with friendly ties to Saudi Arabia and Iran.

It is the sole Gulf country to refrain from participating in a Saudi-led bombing campaign in Yemen, which has exacerbated crippling problems in the Arab world's poorest country.

Houthi rebels have been in control of the capital, Sannaa since 2014 when they ousted Yemeni President Abed Rabbo Mansour Hadi from power.