"The draft law (on ending visa requirements for Turks) is being debated in the European Parliament right now," Oettinger, commissioner for digital economy and society, told several regional German newspapers in an interview published on Tuesday, Reuters reports.

"But I predict that we won't have regulation on visa-free travel before the end of the year," said Oettinger, an ally of German Chancellor Angela Merkel, the key driving force behind the migration deal with Turkey.

Turkish President Tayyip Erdogan must address the EU's concerns regarding the principle of the rule of law, he said, adding: "And that's not what it's looking like at the moment."

He also slammed the Turkish government for shutting down opposition newspapers and intimidating journalists critical of government policies.

The broad post-coup crackdown and calls to reinstate the death penalty for plotters drew concern from Western allies who said Ankara must uphold the rule of law in the country.

Read alsoBloomberg: Revived death penalty in Turkey would end EU talks, Germany saysNearly 20,000 members of the police, civil service, judiciary and army have been detained or suspended since Friday night's failed coup, in which more than 200 people were killed when a faction of the armed forces tried to seize power.

The EU sealed a controversial deal with Turkey in March intended to halt illegal migration flows to Europe in return for financial and political rewards for Ankara.