Dubai:Yemen's Iran-backed Houthis killed at least 58 government troops in missile and drone attacks on Thursday, a military source said, in one of the deadliest days of the country's civil war in four years. The attacks killed at least 58 government troops and injured dozens, according to the military source who spoke on condition of anonymity. Yemen's defence ministry said in a statement that its armed forces would respond to the attacks "at the appropriate place and time". The escalation spilled across the border on Thursday, with Saudi officials saying Houthi attacks wounded 11 civilians in the southern Najran region. Last month, the Houthis killed 16 troops in an attack on government-aligned forces south of the port city of Hodeidah, two medical officials told AFP.