The US-led coalition that has been carrying out air strikes against the Islamic State group in Iraq and Syria killed about 2,500 jihadists last month, a military spokesman said Wednesday. 

"In December, we estimate approximately 2,500 enemy fighters were killed in coalition air strikes across Iraq and Syria," Baghdad-based military spokesman Colonel Steve Warren told Pentagon reporters.

The Pentagon has previously been wary of giving body counts. Wednesday's figures come as officials are keen to portray the IS group as being on the defensive after the jihadists suffered a series of setbacks.