French President Emmanuel Macron said on Monday he would to help relaunch talks to normalize ties between Serbia and Kosovo in the next few weeks.
After meeting his Serbian counterpart Aleksandar Vucic, Macron said he would invite delegations from the two countries to Paris along with German Chancellor Angela Merkel.
An EU-sponsored dialogue between Belgrade and Pristina has been stalled since Kosovo introduced a 100 percent tax on all goods imported from Serbia to put pressure on Belgrade to recognize its sovereignty.
Kosovo declared independence with Western backing in 2008, but Serbia still considers it an integral part of its territory.
Together with its traditional ally Russia, Serbia is blocking Kosovo from joining international organizations including the United Nations, UNICEF and Interpol.
"We are seeing rising tension and sometimes these tensions are fueled here and there by external powers that have an interest in making sure no deal is found," Macron said.
"Reaching an agreement implies that each party abstains from unilateral and non-constructive gestures and, in that respect, developments over the last few weeks have been a concern, and decisions that were against past commitments must be abrogated."
Vucic said he had asked Macron to help Serbia in its bid to join the European Union, but Macron made no promises.
He reiterated his previous view that the EU needed to make decision-making more efficient before Serbia and other countries can join.
Recognizing Kosovo is a precondition for Serbia to join the bloc.
Macron is the first French president to visit Serbia since 2001; a visit planned for last December was cancelled after "yellow vest" anti-government protests turned violent in Paris.
In a sign of increased cooperation, Serbia has agreed to buy the French light surface-to-air missile system Mistral.
During Monday's visit, the two sides signed a letter of intent for construction of a metro in the capital Belgrade.
Serbia and France have intensified economic cooperation in recent years; France's Vinci has a 25-year concession to run Belgrade's Nikola Tesla airport.
Serbia is balancing its relations with Russia, a traditional Slavic and Orthodox Christian ally, with a push to join the European Union and foster ties with NATO, though it wants to remain militarily neutral. In 2016 it agreed to buy nine military helicopters from the European Airbus Helicopters.
Vucic and Macron laid wreaths at a monument built to thank France for helping Serbia during World War I.