The move is part of a package of incentives offered to Turkey

The European Union is set to take a big step on Wednesday toward ending visa requirements for Turkish citizens, as a widely criticised deal to get Turkey to stop migrants entering the EU gathers pace.

The EU's executive commission is expected to invite member states to vote before the end of June to allow Turks on short-term leisure or business stays to enter the EU without visas.

The commission lauded on Tuesday a decree from Ankara to grant visa-free travel in Turkey to the citizens of all 28 EU member states - including Cyprus, which Turkey refuses to recognise in a decades-long stand-off - as meeting "one more of the important benchmarks" for visa liberalisation.

The visa waiver process was started in December 2013 and as of March 4 this year only around half of the 72 conditions had been fulfilled.

"Turkey has made a lot of effort over the past weeks and days to meet the criteria," commission spokeswoman Mina Andreeva said. Suggesting that a green light is imminent, she underlined that the waiver "can always be suspended if the conditions for it are not met".

The move is part of a package of incentives offered to Turkey - including up to six billion euro (£4.75 billion) in aid for Syrian refugees and fast-track EU membership talks - to persuade Ankara to prevent migrants heading to Europe and take thousands who have since March 20 back from Greece.

That deal has raised legal and moral questions, as EU nations unable to agree among themselves about how to handle the refugee emergency chose instead to outsource it to Turkey, where almost three million refugees are staying, most of them people fleeing war in Syria.

Visa liberalisation, which must come by June 30, would be an important sign that the Europeans are living up to their promises. Turkish president Recep Tayyip Erdogan has warned that the whole agreement would collapse if the EU reneges on any pledge.

To secure the visa waiver, Turkey must meet not just technical but also legal and political criteria. They include areas like passport security - few Turks have biometric travel documents - border controls and surveillance, cooperation with the EU on dealing with crime, human rights issues linked to anti-terror and discrimination laws, and the readmission of irregular migrants.

Some politicians are perplexed at how Ankara has been able to meet dozens of conditions within just a few weeks.

"The European Parliament cannot accept endorsing hasty bazaar-style negotiations," Guy Verhofstadt, head of the liberal ALDE bloc, said recently.

"The EU-Turkey deal can only be acceptable, if standards and legality are respected. We cannot outsource our asylum and migration policy to Turkey."

The commission is insisting that Turkey must fully respect all the conditions.

"The onus is on Turkey," commission vice-president Frans Timmermans said last week. "We will not play around with those benchmarks. They are clear, they are legally framed."