Berlin (AFP) - Kosovo's president said Tuesday help from the United States was necessary to resolve a bitter dispute between his country and Serbia, as Europe was too "weak and divided".

A day after a summit of Balkans leaders in Berlin hosted by both German Chancellor Angela Merkel and France's President Emmanuel Macron, Kosovo President Hashim Thaci, told AFP the talks were "disappointing" with "nothing concrete on the table".

Thaci's downbeat assessment came just hours after the summit closed with the Balkan foes pledging to "speed up efforts to implement existing agreements and to re-engage constructively in the normalisation dialogue with the mediation of the EU".

But for Thaci, "It's clear, without the US, nobody can move forward in western Balkan.

"Because, even yesterday, everybody felt that EU is weak and very divided.

Speaking partly in English and partly through a translator, Thaci said: "They have no spirit of leading" such a sensitive process, "and it's very difficult at the same time". 

"The US, they have capacity, they work fast, better and have leadership," he said. 

Thaci pointed to a letter US President Donald Trump sent to him and Serbian President Aleksandar Vucic saying that "it looks they (the US) have ideas and we can find a solution for the final agreement and substance in the framework of this letter".

In comparison, Thaci said last night's summit, which ended in the early hours of Tuesday in Berlin, had brought nothing new to the table.

Asked if Macron and Merkel had put forward new proposals, Thaci said: "No, zero."

"Of course, they wanted to move forward as much as we can, but what really (came out yesterday) is just one point: to continue to sit with each other, to continue in the next meeting in Paris."

"I hope in Paris, we will move in substance of things," he said of the planned follow-up meeting in July.

'Year of agreement?'

EU-brokered talks between Serbia and Kosovo had ground to a halt last year.

The nub of the dispute is Belgrade's denial of the independence of Kosovo, a former province of deep historical and cultural significance to Serbians that broke away in the bloody 1998-1999 war.

The Brussels-led dialogue collapsed several months after talk of possible border changes between the neighbours triggered a stinging backlash last summer.

Critics warned that redrawing the map would be a risky business in the fragile Balkans, a region still recovering from its 1990s wars.

Then came a series of diplomatic clashes between Pristina and Belgrade that deepened their hostility, in particular Kosovo's decision in November to levy a 100-percent tariff on Serbian goods. 

A stalemate ensued.

Kosovo has vowed to keep the tariffs until Belgrade shows openness to recognising independence, while Serbia says it will not talk until the tariff is removed.

But normalising ties with Kosovo and harmonising its foreign policy with that of the EU, are among key criteria Serbia has to meet to join the bloc.

On Monday, Vuvic reiterated that a condition for resuming the talks would be lifting the punitive tariffs -- something firmly rejected by Thaci.

"The dialogue has to be unconditioned: it's not so important what President Vucic said, Kosovo is an independent and sovereign state," said Thaci.

For him, the idea of border changes is an "idea of opponents of the process".

"My idea is very clear: Serbia must recognise Kosovar independence," he said.

Despite the entrenched differences, Thaci remained optimistic, saying he hoped 2019 would be "a year of the agreement between Kosovo and Serbia".