Nagorno-Karabakh, a region with a majority Armenian population but internationally recognised as part of Azerbaijan, is at the heart of a territorial dispute between Baku and Yerevan that has led to two wars.
Azerbaijani President Ilham Aliyev and Armenian Prime Minister Nikol Pashinyan met in Brussels under the auspices of European Council President Charles Michel.
The Armenian Foreign Ministry said the discussions had focused in particular on "the worsening humanitarian crisis in Nagorny Karabakh," and that both sides had "agreed to intensify work aimed at resolving existing problems."
"Our exchanges were once again frank, honest and substantive," said Michel in a short statement at the end of the meeting.
He encouraged both leaders "to take courageous steps to ensure decisive and irreversible progress towards normalisation."
"As a matter of priority, violence and harsh rhetoric must cease in order to create an environment conducive to peace talks."
He announced his intention to organise a further meeting with Aliyev and Nikol Pashinyan in Brussels after the summer, as well as a five-way discussion at the beginning of October in Granada in southern Spain, with French President Emmanuel Macron and German Chancellor Olaf Scholz, on the sidelines of the next summit of the European Political Community.