The European Commission, the executive arm of the 28-nation EU, on Wednesday, May 4 gave conditional backing for Turks to get visa-free travel as part of a deal to solve the migrant crisis, a commissioner said, according to AFP.

"The European Commission is today proposing... to lift the visa requirements for the citizens of Turkey" on condition that Ankara fulfils "as a matter of urgency" criteria set by the EU, according to a document tweeted by Competition Commissioner Margrethe Vestager.

The move is part of a deal in which Turkey is taking back migrants who have crossed over the Aegean Sea to Greece.

But Turkey must still meet EU criteria.

The freedom of speech; the right to a fair trial; and revising terrorism legislation to better protect minority rights - these are just some of the criteria demanded by the EU of countries before it lifts visa requirements, even for short-term travel.

Under the EU-Turkey agreement, migrants who have arrived illegally in Greece since 20 March are to be sent back to Turkey if they do not apply for asylum or if their claim is rejected.

For each Syrian migrant returned to Turkey, the EU is to take in another Syrian who has made a legitimate request.