The EU's police, customs and judicial mission in Kosovo, the bloc's largest ever civilian operation abroad, is being downsized significantly as responsibility shifts to Pristina, officials said Friday.

Hansjoerg Haber, who heads the 3,000-strong EULEX -- the European rule of law mission in Kosovo -- said Kosovo authorities "have made a lot of progress", with police and customs officers in particular now "increasingly professional."

"We can lighten our footprint," he said, announcing that EULEX staff would be cut by 25 per cent from around 3,000 to around 2,250 international and local staff.

After more than three years on the ground, "EULEX needs to adapt and prepare disengagement," said Haber, who is its civilian operations commander. "The Kosovo authorities will have to take on more work and responsibilities."

The focus would increasingly be on justice "where Kosovo needs help," he said, citing war crimes, trafficking, corruption and witness protection.