Fighting continued near the city of Marib in Yemen on Sunday between Iran-backed rebels and forces loyal to Yemen's internationally recognized government.
Last week, security officials said at least 200 fighters were killed in clashes between Yemen's government forces and Houthi rebels in and around the strategic central province of Marib over two days.
Most of the casualties belonged to the Houthi forces, who have recently wrestled from their rivals most of Marib's 14 districts, according to the officials, who spoke on condition of anonymity because they were not authorized to brief the media.
The Houthis have for years attempted to take oil-rich Marib to complete their control over the northern half of Yemen.
The kingdom is leading a military coalition that has been fighting on the government side against the Houthis.
Yemen has been convulsed by civil war since 2014 when the Houthis captured the capital, Sanaa, and much of the north of the country, forcing the internationally recognized government to flee to the south, then to Saudi Arabia.
The Saudi-led coalition entered the war in March 2015, backed by the United States, to try to restore the government to power.
Despite a relentless air campaign and ground fighting, the war has deteriorated largely into a stalemate and spawned the world's worst humanitarian crisis.