The European Union's (EU) high representative for foreign and security policy, Josep Borrell, called on Serbia on Saturday to immediately stop the deploying of the army along the border with Kosovo and withdraw troops deployed so far.
The relocation of Serb troops along the border with Kosovo comes about a week after the September 24 attack on Kosovo Police in Banjska, Zvecan, where a police official was killed.
The EU's chief of diplomacy told some international media that the bloc is discussing with its partners and allies about the current situation in northern Kosovo, where the amount of weapons found by Kosovo Police "is very serious".
Kosovo police found and confiscated an arsenal of weapons after the attack.
The responsibility for the attack was taken by Milan Radoicic, the current deputy chairman of Lista Srpska, kosovo's largest serb party.
Serbia has denied Kosovo's accusations that it was involved in the attack, labelled as terrorist by Kosovo authorities.
"At the same time, the military buildup of Serbia near the administrative border line is very worrying. "This must stop immediately," Borrell said.
He said there is "no room for gathering of the army and security forces on the continent of Europe. Forces must withdraw."
On Friday, the United States called on Serbia to withdraw troops from the border, calling their relocation "very destabilizing development."
Borell expects those responsible for the September 24 attack to be punished and Kosovo and Serbia to return to dialogue.
"We need to go back to the situation in which the parties are talking and return to the EU facilitated dialogue which is the only platform for normalizing relations between them," he added.
The attack came about two weeks after Kurti and Vucic failed to reach an agreement on normalizing relations during the European Union-brokered dialogue summit in Brussels on September 14.
Pristina believes it should be mutual recognition, while Belgrade insists on a compromise solution.
Serbia does not recognize Kosovo's independence, declared in 2008, and has the support of allies Russia and China against it.