At least 50,000 terrorists from Islamic State group have been killed since the US-led coalition started fighting in Iraq and Syria two years ago. A US military official has described the figure as a conservative estimate. <br/><br/>The figure showed air power and a small number of US figures supporting local forces were having an impact, the official said. <br/><br/>The official yesterday said that coalition air strikes could be intensified in places like Mosul, which Iraqi troops are now battling to recapture, but that had to be offset against the risk of civilian casualties. <br/><br/>The US has often been reluctant to provide figures on enemy casualties. But in August, Lt General Sean MacFarland was quoted by the news agency as saying that about 45,000 enemy combatants had been killed. The IS has lost a lot of ground since it reached the high tide of its expansion.