By Eric Jansson in Pristina
Soren Jessen-Petersen, the UN's most senior official in Kosovo, has mounted a robust defence of international policing in the Serbian breakaway province, after Kosovo's prime minister described the work of the UN police there as a "failure".
Mr Petersen called the prime minister's comments "a sweeping statement that cannot stand". He said UN police deserved enormous credit for helping to prepare Kosovo's local forces eventually to assume control of their own affairs.
Bajram Kosumi, the prime minister, issued a broad criticism of UN police's performance in Kosovo since 1999, when Nato bombing pushed Yugoslav forces out of the province to halt ethnic fighting, ushering in a period of international rule.
The UN mission run by Mr Petersen has since functioned as Kosovo's executive, overseeing the work of an elected provincial government. Mr Kosumi described UN policing as a "constant failure" that had jeopardised citizens' trust in international institutions, including the UN.
Mr Petersen also strongly countered public speculation by Avni Arifi, senior aide to Mr Kosumi, that more cases of UN police officers involved in people trafficking might yet be uncovered. Mr Arifi on Thursday told the Financial Times that the arrest of three Pakistani officers working for UN police could point toward a broader scandal.
The officers arrested three weeks ago, whose names are being protected by UN police, were later released by a local, UN-administered court after facing accusations that they had run a ring that illegally smuggled people across international borders.
Mr Petersen said a formal investigation was continuing. UN police had an "image problem" but he cautioned against undermining the reputation of the entire force in Kosovo, comprised of more than 3,700 officers.
"You will always have rotten apples, and it takes only one or two. We are trying very hard to clamp down on any misbehaviour."
He said UN police officers had arrested their colleagues in the case, calling this proof of the force's professionalism and effectiveness.
While running a major policing campaign to fight the illegal traffic in humans, especially for forced prost-itution, the UN in Kosovo has faced a slow trickle of accusations of this kind.
The UN mission has uncovered at least two cases in which UN personnel were accused of related crimes. A scathing report last year by Amnesty International said having thousands of international civilian, police and military personnel in the province was exacerbating, rather than stopping, sex slavery there.