United Nations Secretary-General Ban Ki-moon is welcoming the release of two Saudi Arabian citizens held in Yemen since March 2015.

Ban expressed hope that their freedom will help advance the peace process in the impoverished Arab nation.

U.N. spokesman Stephane Dujarric said Ban thanked the U.N. envoy to Yemen, Ismail Ould Cheikh Ahmed, who helped to secure the unidentified Saudis' release.

Yemen's conflict pits the government, backed by a Saudi-led coalition, against Shiite rebels known as Houthis, allied with a former president. The Houthis took over Sanaa in September 2014, and the Saudi-led coalition began airstrikes against the Houthis in March.

Dujarric said Ban also expressed gratitude to Ansar Allah, the Houthis' political arm, "for facilitating the release as an important confidence-building measure."