PRISTINA -- Serbia ordered its troops on high alert and its ally Russia accused Kosovo of provocation, following a Kosovar police operation in the country’s mainly ethnic-Serb north.
Kosovar officials said that the May 28 raids targeted organized crime groups, but the operation also resulted in the detention of two members of the United Nations mission in Kosovo, including a Russian citizen who was later released.
Authorities in Kosovo said more than 20 people were arrested, mainly police officers, and that 11 were injured during the operation.
The raids fanned Kosovo’s already-tense relations with neighboring Serbia, which does not recognize the 2008 declaration of independence of its former province.
The Kosovar police issued a statement saying those detained were suspected of being involved in "criminal activities." The statement also cited "armed resistance" by ethnic Serbs in Zubin Potok.
The raids that involved special police forces were conducted in other municipalities including Mitrovica South and Skenderaj, they said.
Police chief Rashit Qalaj told a news conference in Pristina that 19 police officers were among those arrested and suspected of smuggling goods into Kosovo.
Eleven were ethnic Serbs, four ethnic Albanians, and four were Bosniaks, Qalaj said.
Five police officers and six civilians were reported injured during the operation.
In Belgrade, Serbian President Aleksandar Vucic put Serbian troops in a state of full alert after learning about the operation, which he said was designed to intimidate minority Serbs.
"If there is any serious threat to the order and life of people in the north of Kosovo…we will protect our people," Vucic said.
Serbia's official news agency, Tanjug, later reported that a column of Serbian Army vehicles packed with troops was heading toward the border with Kosovo.
The United Nations Interim Administration Mission in Kosovo (UNMIK) voiced "great concern" at the arrests of two of its staff members during the police operation, saying they sustained injuries that needed medical treatment.
UNMIK later said that one of them, a Russian national, had been released.
Kosovar President Hashim Thaci earlier said that a Russian citizen who was "camouflaged as a diplomat in order to prevent the police operation" was among those detained.
Prime Minister Ramush Haradinaj tweeted that Kosovo will "treat the case of the Russian 'diplomat' in accordance with international conventions."
"Kosovo and regional countries are familiar with the Russian agenda to destabilize our region." Haradinaj added.
The Russian Embassy in Belgrade in a statement expressed "outrage" at the Russian's detention, demanding that the man be freed immediately and that "all those responsible for this incident be held liable."
In Moscow, Russian Foreign Ministry spokeswoman Maria Zakharova said that Kosovo "provoked" Serbia by sending its police force to enter Serb-populated regions of the former Serbian province.
Zakharova said that the operation "aims to stoke fears into the non-Albanian population" and "seize control over those areas by force."
The European Union, UNMIK, and KFOR, the NATO-led peacekeeping mission in Kosovo, called for calm.
European Commission spokeswoman Maja Kocijancic said Brussels was calling for "utmost restraint" between the sides.
Kocijancic also warned Kosovar authorities that police operations need "to reinforce and not weaken" EU-brokered efforts to normalize relations between Belgrade and Pristina.
UNMIK urged "all parties to abide by the principles of rule of law and dignity for all to life and liberty, and to help restore calm and security in the area.”
KFOR said in a statement that the operation was only conducted by the Kosovar police and it did not involve the military.
The peacekeeping mission also called on “everybody to stay calm and not to escalate to the use of violence."
Belgrade lost control over Kosovo, a region with an overwhelmingly dominant Albanian majority, after a NATO air campaign in 1999.
Kosovo's ethnic Albanian majority declared independence from Serbia in February 2008. Although more than 110 countries recognize Kosovo, Belgrade and Moscow do not.
The northern part of Kosovo remains in a state of lawlessness as the majority Serbs, backed by Belgrade, have rejected Pristina's jurisdiction over them.
Organized crime thrives in the region, with suspects easily finding refuge from police across the porous boundary.