WASHINGTON (Reuters) - A U.S. citizen who was detained for more than a year and a half by the Houthi faction in Yemen has been released, Secretary of State John Kerry said on Sunday.

Wallead Yusuf Pitts Luqman was freed with assistance from Oman, Kerry said in a statement, adding that he and his aides had been focused on the case since Luqman was detained.

"We also recognize this positive gesture by the Houthis," Kerry said.

The Houthis, a Shiite Muslim group, and forces loyal to former Yemeni president Ali Abdullah Saleh are fighting a civil war against ousted, but internationally recognized President Abd-Rabbu Mansour Hadi, who is backed by a Saudi-led coalition.

Luqman is the third American held by the Houthis to be released since mid-October. The government of Oman, a U.S. ally in the Gulf, mediated in each case.

News reports have described Luqman as a former U.S. Marine who was abducted in April 2015 while trying to leave Yemen, where he had been teaching English.

Following the release of two U.S. citizens from Yemen on Oct. 15, a woman who identified herself as Luqman's wife urged his release.

"While other Americans continue to be released, Wallead is left behind. Wallead has missed too much, his children need him in their life, he needs to come home now," she wrote on Facebook.

A senior State Department official said Kerry was personally involved in securing Luqman's release, working closely with Omani officials and meeting with Luqman's family a few weeks ago to update them on his efforts.

Kerry called the family today to make sure they knew he was getting released, said the official, who spoke on condition of anonymity.

Oman's state news agency ONA reported earlier on Sunday that an American held in Yemen, whom it did not identify, was released in the Houthi-controlled Yemeni capital of Sanaa and flown to Oman aboard an Omani royal air force jet.

(Reporting by Warren Strobel; Additional reporting by Lesley Wroughton; Editing by Chris Reese)