Brussels hosted national security advisors from Azerbaijan and Armenia, along with those of France and Germany, after Baku's lightning offensive last week.

The meeting came as thousands of ethnic Armenian residents fled Nagorno-Karabakh out of fear following Azerbaijan's victory over rebel forces.

"The EU stressed the need for transparency and access for international humanitarian and human rights actors and for more detail on Baku's vision for Karabakh Armenians' future in Azerbaijan," an EU statement said.

Brussels said the talks "allowed for intense exchanges between participants on the relevance of a possible meeting of the leaders" of Azerbaijan and Armenia at a European summit in the Spanish city of Granada on October 5.

Prior to Baku's lighning assault, the EU had been involved in mediation efforts aimed at securing an enduring peace between the two feuding neighbours.

The statement said the representatives from Armenia and Azerbaijan had discussed "possible concrete steps" to advance the peace process including border delimitation, and security, connectivity and humanitarian issues.

"Concrete action and decisive compromise solutions are needed on all tracks of the normalisation process," the EU said.