The EU vowed Wednesday to propose visa-free travel for Turks next month if Ankara meets the terms of a landmark migrant deal, as it tried to defuse a row with Turkey's leaders.

Brussels made the announcement after Turkish Prime Minister Ahmet Davutoglu warned that Ankara could tear up the March 18 agreement if the European Union did not implement the visa pledge.

EU migration commissioner Dimtris Avramopoulos said a new EU report on the deal showed that ‘progress has been made’ in cutting the numbers of migrants coming to Europe from Turkey.

‘We have already seen a sharp drop in the number of people crossing irregularly the Aegean from Turkey into Greece, which means the activities of smugglers in the area have been hit,’ he told a news conference.

As a result, the European Commission, the 28-nation bloc's powerful executive arm, would now present a visa recommendation on May 4 to be approved by member states.

‘If Turkey takes the necessary measures to fulfil the remaining benchmarks, the report will be accompanied by a legislative proposal for transferring Turkey to the visa-free list,’ the EU report said.

Avramopoulos stressed that ‘no visa liberalisation will be offered if not all benchmarks are met.’

The commission also urged Turkey to do more to improve conditions for migrants sent back from Greece under the deal.

‘Further efforts are required by Turkey to make sure that those who need international protection receive the kind of support they most require,’ the report said.

- 'Not a threat' -

Under the deal Turkey agreed to take back all migrants arriving in the Greek islands, in an effort to relieve the pressure on the European Union that saw one million migrant arrivals since early 2015.

In return Europe promised to resettle one Syrian refugee for every Syrian taken back by Turkey, to grant visa-free travel to Turks within the border-free Schengen zone and to reassess Turkey's stalled EU membership bid.

But the EU insists that Turkey must meet a long list of conditions before allowing visa-free travel, a step that many rightwing politicians in Europe have seized on amid growing fears about immigration.

Turkey has expressed growing anger about what it sees as more European dithering.

The issues are coming to a head as German Chancellor Angela Merkel, EU President Donald Tusk and other top officials prepare to travel Saturday to the Turkish city of Gaziantep close to the Syrian border to discuss implementation of the migrant deal.

President Recep Tayyip Erdogan warned the European Union Tuesday it needs Turkey more than Ankara needs the bloc.

Davutoglu meanwhile said there was a ‘mutual commitment’ under the deal, adding: ‘If the EU cannot take the necessary steps required of it then of course it cannot be expected of Turkey to take these steps.’

Tensions have also been fuelled by a European Parliament report published last week that accused Turkey of backsliding on democracy and pressure from Ankara on Berlin to prosecute a German comic over a poem satirising Erdogan.

Avramopoulos however tried to take some of the heat out of the row.

‘We do not consider the statement by leaders as a threat. This deal is based on trust,’ he said.

Rights groups have criticised the deal as effectively allowing the mass expulsion of refugees from Europe.

Warnings that the deal could just push migrants to other route gained force Wednesday when the UN refugee agency said it feared 500 migrants from Africa had drowned in the Mediterranean on April 16 while somewhere between Libya and Italy.