BATROVCI, Serbia (Reuters) -Kosovo said 10 off-duty police officers were detained on Wednesday in Serbia for questioning, including a deputy police commander, while passenger buses using Serbian territory as transit were halted for hours.
"Ten Kosovo police officers, Albanians and Serbs, have been detained at border crossings...five of them have been released and five are still in custody," Kosovo's Interior Ministry said in a statement.
There was no immediate reaction from Belgrade.
Earlier, at least six buses from Kosovo were halted for hours by Serbian police at a border crossing with neighbouring Croatia, before being allowed to continue their journeys, passengers said.
The Serbian Interior Ministry said at the time that Serbian police had not detained anyone or tried to prevent entry and passage to Kosovo citizens, but that controls and security checks had been tightened which led to longer waits.
"All citizens from... Kosovo are allowed unimpeded entry," it said in a statement.
The tightened checks followed a decision by the Parliamentary Assembly of the Council of Europe (PACE) to recommend that Kosovo should be invited to become a member of the Council of Europe, a top European human rights body.
In a statement on social media platform X, Kosovo's Prime Minister Albin Kurti called the move a retaliation.
"A day after PACE voted in favour of Kosovo's membership in CoE, Serbia retaliates against Kosovo civilians," he said.
Serbia has rejected such accusations.
The Kosovo ministry said the deputy Kosovo police commander was Dejan Jankovic, a Kosovo Serb, who was among those still in detention. All police officers were off duty.
The passengers from buses that arrived at the crossing late on Tuesday said they had their documents taken for checks and were told to wait.
The buses were allowed to enter Serbia and proceed to Kosovo on Wednesday afternoon, after a wait of almost 20 hours, said Gazmend Zhitia, a passenger.
"They (the police) were focused on some checks of Albanians over the war which was in 1999," Zhitia said.
Similar delays were reported by Kosovo travel agencies at the Serbian border with Hungary.
European Union spokesman Peter Stano said in a statement that the bloc was aware of the situation and that Serbia's move constituted a violation of an agreement on freedom of movement between Belgrade and Pristina.
Kosovo, which has an ethnic Albanian majority, declared independence from Serbia in 2008 after a guerrilla uprising and a 1999 NATO intervention.
Serbia, backed by its ally Russia, China and five EU members, is opposing Kosovo's independence and membership in international organisations.
Belgrade and Pristina have spent years in talks mediated by the EU to normalise their relations, but the progress is slow and marred by crises and flare-ups of violence.