Yemen's government forces said Sunday that more than 500 soldiers were killed and nearly 1,500 injured during month-long clashes with Houthi rebels along the country's western coast, as the insurgent group executed a major advance toward the strategic Bab al-Mandab Strait.

In a statement broadcast on media, the government's National Resistance Forces reported that the casualties were recorded between Aug. 9 and Sept. 10. The forces also claimed that over 1,000 Houthi fighters were killed and thousands more wounded, though these figures could not be independently verified.

Military officials said the fighting began with Houthi missile, drone and explosive-boat strikes before expanding from Hays, in the southern part of Hodeidah province along the Red Sea, to multiple battlefronts in neighboring Taiz province in the southwest.

The casualties follow a sweeping offensive launched by the Houthis on Sept. 3 that rapidly redrew front lines along Yemen's Red Sea coast, resulting in the capture of several government-controlled areas across Hodeidah and Taiz provinces.

Rebel forces captured the strategic port city of Mocha on Thursday before pushing south into the Bab al-Mandab area on Friday. They seized Mayun Island in the center of the strait, tightening control over the crucial shipping chokepoint connecting the Red Sea to the Gulf of Aden.

Houthi troops subsequently advanced farther south toward neighboring Lahj province, where retreating government troops had regrouped, bringing active combat closer to Aden, the temporary seat of Yemen's internationally recognized government.

Yemen's civil conflict originally erupted in late 2014 when Houthi forces captured the capital, Sanaa, along with large portions of northern Yemen. The takeover prompted a Saudi-led military coalition to intervene in March 2015 to support the country's internationally recognized government.