Greek defence minister Panos Kammenos has threatened to overflow Europe with migrants including militants of the Islamic State (Isis) if eurozone countries reject Greece's debt renegotiation plans.

The incendiary comments came ahead of Monday's Eurogroup meeting in Brussels, where Athens is due to give detailed plans of its debt and growth terms.

Kammenos said that "if they deal such a blow to Greece, then they should know that the migrants will receive (travel) documents and head to Berlin", according to Dpa news agency.

The far-right leader of Independent Greeks, who has struck a deal with leftist Prime Minister Alexis Tsipras, added that if there were members of IS among the refugees it is entirely Europe's fault for refusing to soften the stance on Greece.

Kammenos's words came after finance minister Yanis Varoufakis said in an interview with Italian newspaper Corriere della Sera that if a deal was not agreed "we will resort to the Greek people either through elections or a referendum".

Varoufakis never mentioned the words "for the euro", as some reports suggested. The statement, nonetheless, was interpreted by some as a threat to leave the eurozone if talks failed.

The finance minister criticised the report as "wilful attempts to undermine the good course" of Greece's new politics.