Western powers on Tuesday urged foes Serbia and Kosovo to reboot their stalled dialogue "with urgency", warning that the lack of progress is hindering their dreams of joining the European Union.
Serbia and its former province Kosovo, which is mainly ethnic Albanian, still have a bitter and tense relationship two decades after Pristina broke away in a separatist war and went on to declare independence.
EU-led talks to normalise their ties have sputtered out in recent months over a series of diplomatic clashes.
In a joint statement, the governments of the US, UK, France, Germany and Italy called on the neighbours to "restart the EU-led Dialogue with urgency".
"The status quo prevents progress on Kosovo's and Serbia's path towards the European Union (EU) and is simply not sustainable", it added.
The governments said they were willing to become more involved in the talks -- but only if "you both signal a willingness to compromise, remove obstacles and resume discussions".
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The statement urged each side to extend an olive branch.
"For Kosovo, that means suspending the tariffs imposed on Serbia," the governments said, referring to a 100 percent tax slapped on Serbian goods last November.
The countries then urged Serbia to halt its "de-recognition campaign against Kosovo", referring to Belgrade's efforts to sway other countries to revoke their recognition of Kosovo's statehood.
After the EU-led talks hit a wall last year, Germany and France took their own initiative to try to restart the dialogue, holding a summit in Berlin in April.
But no progress was made and a planned follow-up meeting in July was later scrapped.
Serbia lost control of Kosovo after a NATO bombing intervention forced its troops to withdraw from a war with ethnic Albanian separatists in 1999.
A decade later Kosovo declared independence, a move recognised by the US and most of Western Europe.
But Belgrade and its allies Moscow and Beijing have never accepted its statehood, effectively shutting Kosovo out of the United Nations.