ARBIL, Iraq (AFP) -- Nearly 1,000 Iraqi Kurdish peshmerga fighters have been killed battling the Islamic State jihadist group since June, a senior security official said on Wednesday.

Jabbar Yawar, the secretary general of the ministry responsible for the  peshmerga, told a news conference that 999 Kurdish fighters were killed and 4,569 wounded between June 10 and February 3.

Previous casualty figures released on December 10 put the toll at 727 killed and 3,564 wounded.

IS spearheaded a sweeping offensive that has overrun much of Iraq's Sunni Arab heartland since June, presenting both an opportunity for territorial expansion and a threat to the country's three-province autonomous Kurdish region.

Several federal army divisions collapsed in the early days of the assault, clearing the way for the Kurds to take control of a swathe of disputed territory they have long wanted to incorporate into their autonomous region over Baghdad's objections.

But after driving south towards Baghdad, IS turned its attention to the Kurds, pushing them back towards regional capital Arbil in a move that helped spark U.S.-led air strikes against the jihadists.

Bolstered by the air campaign as well as foreign military advisers and trainers, Kurdish forces have clawed back significant ground from IS.

The conflict is redrawing some of the de facto internal boundaries of Iraq in favor of broader Kurdish control in the north.