The crisis in Greece was not triggered by the austerity memorandums but an unjustifiably expansive fiscal policy, where state spending far outstripped state revenues, Bank of Greece governor Yannis Stournaras said on Monday at an event organised by the 'Citizens' Movement'.

"We express Greece's solidarity with the Belgian people. Fear, religious hatred and racism should not defeat Europe," Prime Minister Alexis Tsipras posted on Twitter following the attacks in Brussels earlier on Tuesday.

The deal between the EU and Turkey on returning migrants who cross the Aegean sea to Greece has come into effect. Any refugees arriving in Greece can now expect to be sent back to Turkey if they do not apply for asylum or if their claim is rejected.

Two explosions were heard at Brussels airport early on Tuesday morning and Belgian media said several people were injured. Belgian media note that at least 11 persons have been killed. Images of broken windows and several injured people have been released.