ALDE MEP Marietje Schaake has urged European Commission First Vice-President Frans Timmermans and the Dutch Prime Minister Mark Rutte to demand guarantees from Turkey concerning the safeguarding of the rule of law, human rights and freedom of the press.
The Dutch deputy told this website, "The most pro-European citizens in Turkey are losing their confidence in the EU. They feel betrayed because European leaders do not criticise the deteriorating rule of law and human rights situation."
She added, "This becomes even clearer now that the EU and Turkey made a deal about refugees."
She was speaking on the last of a three-day visit to Ankara and Istanbul with the European Parliament subcommittee on human rights.
The MEP went on, "In addition, there are concerns about the way these refugees are being treated after the deal.
"There is a huge difference between agreements and laws in theory and in practice. Timmermans and Rutte have to demand more guarantees from the Turkish authorities."
"President Erdogan silences critical voices in a systematic way while working on a presidential system that gives him even more power.
"People are afraid to speak out because journalists, academics and citizens are prosecuted on unclear grounds or on the basis of anti-terror laws. NGOs and human rights defenders fear suspects do not get a fair trial."
"We leave Turkey at a critical moment," said Schaake, pointing to the fact that, on Friday, the Turkish Parliament will vote about the lifting of immunity for 130 its MPs.
She said, "This will have direct consequences for 50 of the 59 members of the pro-Kurdish HDP party. Next to that, the AK party will elect a new leader, who also becomes the new Prime Minister of Turkey. The coming week will set the tone for Turkish politics the coming years and will have great impact on the relationship with the EU."
Meanwhile, the European Commission has adopted its latest progress report on the EU's emergency relocation and resettlement schemes.
It assesses actions taken up to 13 May 2016 and says that, overall, progress remains unsatisfactory since its second report.
It says few relocations have taken place since mid-April, though plans for future relocations have been strengthened.
The Commission, in the report adopted on Thursday, says that some progress has been made on resettlement as part of the implementation of the EU-Turkey deal agreed earlier this year.
But it says that this "must be accelerated to avoid migrants returning to irregular routes."
Greater efforts on relocation are "increasingly urgent" given the humanitarian situation in Greece and the increase in arrivals to Italy, says the executive.
Speaking in Brussels, European Commissioner for migration, home affairs and citizenship, Dimitris Avramopoulos said: "We cannot be satisfied with the results achieved so far. More has to be done, and swiftly."
The Greek official went on, "We need to quickly respond to the urgent humanitarian situation in Greece and prevent any deterioration of the situation in Italy. The planning we see for upcoming relocations must be delivered."
He has urged member states to "get ready to move at last."
"We need," he added, "to increase resettlements, mostly from Turkey, but also from other countries such as Lebanon and Jordan. Our recent progress in breaking the smugglers' business model is only sustainable if a safe legal channel also opens for asylum seekers. It is important to speed up the pace and deliver fully on the EU-Turkey agreement."