At least 44 people were killed as heavy fighting continued between Yemeni security forces and the Houthi militia in the oil-rich rovince of Marib amid intensified airstrikes, a military official said."Tweenty-eight members of the Houthi rebel group and 16 soldiers of the pro-government Yemeni forces were killed during the past 24 hours in Marib's fighting," the official told Xinhua news agency on Sunday.The Houthi fighters carried out simultaneous attacks against several positions controlled by the pro-government forces in the southern and northwestern areas of Marib, he said.He clarified that the Houthis used explosive-laden drones and missile attacks to target the pro-government forces stationed in Marib."The Houthis succeeded in achieving limited on-ground progress after launching a number of multi-pronged attacks in the fighting with the pro-government forces," he added.Warplanes of the Saudi Arabia-led coalition carried out a series of airstrikes targeting Houthi-controlled areas and reinforcements in Marib's western part, according to the official.The Houthis began in February a major offensive on Marib in an attempt to seize control of the oil-rich Yemeni province, the government's last northern stronghold.Yemen's civil war flared up in late 2014 when the Iran-backed Houthi group seized control of much of the country's north and forced the internationally recognized government of President Abd-Rabbu Mansour Hadi out of the capital Sanaa.The Saudi-led Arab coalition intervened in the Yemeni conflict in March 2015 to support Hadi's government.