The Kosovo Appellant Court rejected defence appeal against the detention of those arrested on May 28 and extended the custody for 31 men suspected of corruption, smuggling and abuse of office, the Beta news agency reported on Thursday.
The ruling said the detention had to be extended due to the possibilities of suspects tampering with evidence, influencing the witnesses or fleeing.
On May 28, the Kosovo police arrested Albanian, Serb and Bosniak police and customs officers as well as civilians in several areas.
The arrests, mostly in northern Kosovo populated by a majority of Serbs, reportedly took place as a part of the police activities to curb the organised crime.
The suspects included Serb, Albanian and Bosniak police and customs officials and civilians.
Two UN Mission in Kosovo (UNMIK) members, one international and one local, were also arrested and beaten. A Russian man was later transferred to Belgrade for medical treatment, while Pristina declared him persona non grata, claiming he was a spy disguised as a UN employ.
The arrest of the UN staff caused condemnation from the world top organisation.