PRISTINA, Kosovo (AP) — A powerful explosion damaged a water canal and temporarily cut water and power supplies to Kosovo’s cities, the prime minister said Saturday, blaming groups supported by Serbia. At least eight people were arrested.

Prime Minister Albin Kurti said the blast on Friday in Vrage, 60 kilometers (37 miles) north of capital Pristina, disrupted the supply of water to some cities and major power plants. It followed two other explosions in previous days on buildings of a police station and local authorities in the same area in the north of the country, mostly populated by the ethnic Serb minority.

About 15 to 20 kilograms (30 to 45 pounds) of explosives were used to damage the critical infrastructure, according to Kosovo police chief Gazmend Hoxha.

Kurti blamed “official Belgrade and its criminal structures led by Milan Radoičić, supported by Serb institutions and Serbia President Aleksandar Vučić.”

Radoičić, a politician and wealthy businessman with ties to Serbia’s ruling populist party and Vučić, was among 45 people charged in Kosovo in connection with a gunfight last year in which a Kosovar police officer was killed following an incursion by heavily armed Serb gunmen.

Only three Serbs have been arrested and the others are at large, including Radoičić, who Pristina says is protected by Belgrade.

Kosovo police have detained eight people suspected of being part of the attack, according to Interior Minister Xhelal Svecla.

A big cache of weaponry, ammunition, military and police uniforms, cash and other items were confiscated at 10 locations in the north.

Serbia Foreign Minister Marko Đurić condemned Friday’s explosion but also criticized Kurti’s “ethnonationalist regime” rushing “to point fingers at Belgrade without evidence.”

“We believe that such premature accusations are a deliberate diversion,” Đurić said. “These baseless allegations undermine efforts for constructive dialogue and serve only to escalate tensions in an already delicate situation.”

The European Union and the United States strongly denounced the explosion and demanded that the perpetrators are brought to justice.

EU foreign policy chief Josep Borrell spoke on the phone with Kurti to condemn the “despicable act of sabotage on Kosovo’s critical civilian infrastructure” and he called “on all stakeholders to cooperate fully with the Kosovo authorities.”

The U.S. Embassy in Pristina said that “these violent actions have no place in a democratic society, and those responsible for these criminal attacks against the legitimate authorities of the Republic of Kosovo should be held accountable.”

Story Continues