As the EU readied to open its door to Serbia in reward for easing ties with Kosovo, the bloc's chief diplomat Catherine Ashton on Thursday hailed the premiers of both sides for a peace drive that could foster regional stability.

After 200 hours of talks at 20 meetings in Ashton's sixth-storey Brussels office, the work done by the prime ministers of Kosovo and Serbia, Hashim Thaci and Ivica Dacic, "gives a certainty to the future" in the Balkans, she said.

Serbia on Tuesday won the European Union's blessing to kick off talks on joining the bloc on January 21 in recognition of its efforts in normalizing ties with Kosovo.

European affairs ministers set the date after having "acknowledged reform and normalization efforts" by the Balkan nation, the bloc's Enlargement Commissioner Stefan Fuele said.

Forensic experts have discovered human remains in a suspected mass grave in Serbia, believed to contain the bodies of Kosovo Albanians killed during the 1998-1999 war, officials said Friday.

"During the site assessment at the Rudnica quarry in the municipality of Raska, Serbia," Serbian authorities, EU-led justice and police mission in Kosovo (EULEX) and Pristina's forensic experts "discovered human remains," EULEX said in a statement.

Hardline nationalists took top posts in Kosovo's capital as well as the main Serb-populated town in the breakaway territory in local elections, preliminary results showed Monday.

The electoral commission said the capital Pristina was won by Shpend Ahmeti of the nationalist Self Determination movement, which opposes the presence of the European Union and NATO in Kosovo as well as any talks with Serbia.

Croatian border police have made their biggest ever seizure of undeclared cash, discovering almost five million euros ($7 million) in a truck during a routine check on the frontier with Serbia, the interior ministry said Thursday.

The 4.75 million euros was found at the Tovarnik border crossing in a truck with Slovenian registration on Tuesday, the ministry said in a statement.

The premiers of Kosovo and Serbia, Hashim Thaci and Ivica Dacic, vowed Wednesday to keep a peace deal on track despite election violence by Serb extremists in Kosovo.

"Both governments condemned the incidents," Thaci said as election officials in Kosovo ordered a re-run vote in a town where Serbs stormed a polling station and destroyed ballot boxes on Sunday.

Serbia's war crimes prosecutor on Wednesday charged two army officers with the murder of at least 27 Kosovan civilians including a young child during the 1998-1999 war.

Pavle Gavrilovic and Rajko Kozlina are charged with committing a war crime against civilians in March 1999 in the southern Kosovo village of Trnje, the prosecutor said in a statement.

NATO head Anders Fogh Rasmussen on Monday "strongly condemned" the violence that marred key weekend polls in Kosovo and said the military alliance was committed to maintaining its presence there.

Rasmussen said NATO troops in Kosovo stepped in at the request of the European Union on Sunday, when Serb extremists stormed a polling station in Kosovska Mitrovica, the main Serb-populated town in the ethnically divided territory.

Violence and low turnout in Kosovo elections underscored the deep divisions in the territory and dealt a blow to Belgrade, which had sought to further its EU membership bid by urging ethnic Serbs to vote peacefully.

The weekend vote, the first Belgrade has backed since ethnic-Albanian majority Kosovo proclaimed independence in 2008, was seen as a test of an April deal brokered by Brussels to normalize ties between the former foes.

Polls opened Sunday in key local elections in Kosovo that are being closely watched by the European Union amid fears of a boycott by minority Serbs, voting for the first time since independence in 2008.

The election of deputies and mayors in 36 Kosovo municipalities is seen as a key test of relations between Pristina and Serbia after an historic EU-brokered deal to improve ties.