File photo. High Representative of the European Union Josep Borrell arrives for a Special European Council meeting in Brussels, Belgium, February 20, 2020. [Pool/EPA/EFE]

The fighting around the Syrian rebel stronghold of Idlib "represents a serious threat to international peace and security" with grave humanitarian consequences for the region and beyond, he said in a statement. The EU "needs to redouble efforts to address this terrible human crisis with all the means at its disposal," Borrell said, adding that he’s calling for an extraordinary meeting of the Foreign Affairs Council next week to discuss the unfolding situation. Borrell said the meeting is being organised particularly at the request of Greece, which faces a buildup of thousands of migrants on its border with Turkey.

The flow of migrants across Turkey to Greece's border in particular has revived EU fears of a reprise of the 2015 refugee emergency. That inflow of mostly Syrian asylum-seekers was stemmed in 2016 by a deal with Ankara called the EU-Turkey Statement.