SANAA, YEMEN:  Twenty-two members of the United Arab Emirates' military were killed while taking part in Saudi-led operations in Yemen against Shiite rebels known as Houthis, the official news agency WAM said Friday, the largest single loss for the Gulf nation's military to date in the war.

Pro-government Yemeni security officials said the troops were killed Friday when a Houthi missile hit a weapons storage depot near their position in the province of Marib. Officials from the Houthi media office in Sanaa confirmed they fired a Soviet-era Tochka missile.

The WAM news agency didn't specify the role of the personnel in Yemen. The seven-state Emirates federation is one of the most prominent members of the Saudi-led coalition, which aims to roll back gains by the Shiite rebels and their allies in the deeply impoverished Arabian Peninsula country.

Fighting in Yemen pits the Houthis and army units loyal to former President Ali Abdullah Saleh against forces loyal President Abed Rabbo Mansour Hadi, who is in self-imposed exile in Saudi, as well as southern separatists and local militias.

The Saudi-led and US-backed coalition has been launching airstrikes against the rebels since March, in an operation that aims to roll back gains by the Shiite rebels and their allies. Houthis have captured more territory around Yemen after taking control of the capital, Sanaa, last September.

Clashes between Houthis and pro-government forces, as well as airstrikes from the Saudi-led coalition, intensified this week in Marib as the opposing sides gear up for a critical battle over the coming days.

Pro-government forces want to clear Marib province of Houthi fighters, then proceed on to Jawf province, then to Saada, the Houthis' stronghold in the north, the security officials said.

They spoke on condition of anonymity because they weren't authorized to brief reporters.