By Gabriela Baczynska and Robin Emmott

BRUSSELS (Reuters) - The European Union voiced grave concern about Turkey's crackdown on opponents since a failed July coup in a highly critical report on Wednesday that made clear that Ankara's prospects of joining the bloc have become ever more distant.

Turkey has rolled back the independence of the judiciary, freedom of expression and other fundamental democratic standards since the coup attempt, the EU said in its most hard-hitting annual report on the country's long-running membership bid.

"The coup attempt of July 15 was an attack on democracy per se. Given the seriousness of the situation, a swift reaction to the threat was legitimate," the EU's top enlargement official, Johannes Hahn, said.

"However, the large scale and collective nature of measures taken over the last months raise very serious concerns.

"Turkey as a candidate country must fulfill the highest standards in the field of the rule of law and fundamental rights. In this year's report we therefore stress Turkey's backsliding in the area of rule of law and fundamental rights."

The report risks further damaging the EU's relations with a country it is relying on to restrict the flow of migrants and refugees from Syria and elsewhere.

Turkey's minister for EU Affairs dismissed the report as "far from constructive" and said that parts of it lacked objectivity.

"The report does not serve to benefit EU-Turkey ties," Omer Celik told a news conference in Ankara, adding the bloc now lacks the vision of its founders. "Stronger bridges need to be built between the EU and Turkey."

Earlier, President Tayyip Erdogan showed his frustration with the long stalemate over membership, saying the EU should take its final decision on Turkey's application quickly.

"Reassess it, but do not delay in reassessing it. Make your final decision," Erdogan said in a televised speech.

"SERIOUS QUESTIONS"

The post-coup crackdown, which has seen more than 110,000 soldiers, judges, teachers, journalists and others detained, dismissed or suspended, has shocked the EU as it tries to work with Ankara on migration and countering terrorism.

The EU has stepped up its criticism of Ankara since its arrest of prominent Kurdish lawmakers last week, and it said it would be Erdogan's fault if Turkey failed to meet criteria for a promised removal of visa requirements for visiting Europe.

The report said Turkey's anti-terror laws were being applied too broadly. "The measures taken since July... raise a number of very serious questions going to the heart of the rule of law," Hahn said.

"These various actions, including considerations on reintroducing the death penalty, seem to be increasingly incompatible with Turkey's official desire to become a member of the EU. It's time Ankara tells us what they really want."

However, Celik said the report's criticisms on Turkey's judiciary and basic rights was "far from objective". He also rejected that Turkey used disproportionate force in the crackdown following the July 15 coup.

In a separate interview with Reuters, Hahn said Turkey's EU candidacy was hanging in the balance.

Luxembourg and Austria, as well as some European lawmakers called on the bloc to halt membership talks with Turkey or punish it with other sanctions.

But Germany, the bloc's top power, opposes sanctions now and Chancellor Angela Merkel was a key driving force behind a March migration deal with Ankara that cut arrivals of refugees and migrants to Europe via Greece to a trickle after a mass and uncontrolled influx last year.

(Additional reporting by Tulay Karadeniz and Ece Toksabay in Ankara; Writing by Gabriela Baczynska; Editing by Ralph Boulton)