Four US citizens have been imprisoned by Iran-backed Houthi rebels in Yemen, media reports said Sunday.
None of the captured Americans are US government employees, US officials told the Washington Post daily.
"The Washington Post is withholding some details about the prisoners at the request of US officials and relatives who cited concerns for their safety," the daily said.
The paper wrote that three of the Americans worked in private-sector jobs while the fourth had dual US -Yemeni citizenship.
According to the officials the Americans are believed to be held at a prison in the Yemeni capital Sanaa and the efforts to release them have stalled.
The daily also claimed that a fifth American named Sharif Mobley has been held by the Houthi rebels on terrorism charges brought against him in 2010 by the previous Yemen government.
Fractious Yemen has remained in turmoil since last September, when Houthi militants overran capital Sanaa from which they have sought to extend their influence to other parts of the country.
On March 25, Saudi Arabia and its Arab allies began an extensive air campaign targeting Houthi positions across Yemen.
Riyadh says its campaign comes in response to appeals by Yemen's embattled President Abd Rabbuh Mansour Hadi for military intervention against the Houthis.
