The migration deal struck between the European Union and Ankara should be separate from Turkey's negotiations to join the bloc, the European Parliament stressed on Thursday, as pressure grows on the country to improve its human rights record.
The European Parliament accused Turkey of "serious backsliding on fundamental freedoms" in a statement.
Turkey began negotiating to join the EU in 2005, though the country is still far from obtaining membership.
Ankara's relationship with Europe has increased in importance in recent months because of the refugee crisis, as many migrants were departing from Turkey.
The deal has been criticized by humanitarian aid organizations and human rights groups. In Turkey, opposition parties have also voiced concern EU realpolitik was putting the migration issue ahead of concerns about the Turkish government's policy.
Earlier Thursday, a top European human rights official voiced concern over measures taken by Turkish authorities in recent months to deal with domestic conflict, including their use of strict curfews, widespread destruction and limits on free speech.
Nils Muiznieks, the Council of Europe's human rights commissioner, said after a visit to Turkey that he has "serious doubts about the legality" of the round-the-clock curfews the state employs in civilian neighbourhoods as it battles Kurdish militants.
He also expressed concern over the "shocking scale" of damage to homes and buildings in south-eastern Turkey, while also condemning all forms of terrorism by militants targeting the state and civilians.
Turkey considers the armed Kurdistan Workers' Party (PKK) a terrorist group. The militants and the state have been locked in conflict for more than three decades, with many among the Kurdish minority complaining of systemic discrimination.
After a two-year ceasefire broke down in July, hundreds of people, including many civilians, have been killed, and hundreds of thousands in the mostly Kurdish south-east have been displaced.
The European Parliament urged Turkey to return to peace talks and called on the PKK to lay down arms. But Turkish officials have indicated they will not again engage the PKK in talks.
Both the parliament and the human rights expert were alarmed by crackdowns on the media and free speech.
"Long-standing problems concerning freedom of expression, arising from Turkish legislation and the practice of the judiciary, have also been severely exacerbated in this tense environment," according to a statement from Muiznieks' office.
Muiznieks also noted that several academics were in jail for signing a peace petition, and nearly 1,850 people were facing criminal proceedings for allegedly insulting President Recep Tayyip Erdogan.
An increasing number of websites are blocked in the country. Under a recent media crackdown, prominent journalists were on trial and newspapers have been taken over by the government.
According to the Dogan news agency, fresh charges were brought Thursday against six people for insulting the president.
The US State Department, in its annual human rights report released this week, warned Turkey was pressuring the media and restricting freedom of the press, including through the use of a law outlawing “insulting” the president.
The report was also critical of human rights abuses in the south-east, including civilian deaths and the curfews.
Recent weeks have seen Turkish security forces clamp down on smugglers operating in the Aegean Sea route to Greece, cutting the number of migrant arrivals to Europe drastically.
The European Union registered around 1 million asylum seekers last year, many of whom entered the bloc via Greece, which has struggled to cope with the influx.
Greece has started to return several hundred migrants to Turkey as part of the deal, which Ankara hopes will see the EU give the country 6 billion dollars in aid for Syrians and visa free access for Turkish citizens to the Schengen Zone.
However, the EU legislative branch said that "outsourcing the refugee crisis to Turkey is not a credible long-term solution to the problem" and refugees needed legal routes to escape hardships.