* Erdogan makes first visit to Brussels in five years
* Corruption scandal likely to overshadow trip
* Purges of police, judiciary, raise EU alarm
* Erdogan vows to press on with judicial reform bill
By Orhan Coskun and Adrian Croft
BRUSSELS, Jan 20 (Reuters) - Rocked by a corruption scandal, Turkey looks further than ever from its goal of European Union membership as Prime Minister Tayyip Erdogan visits Brussels this week in the midst of a crackdown on the judiciary and police.
Erdogan has purged hundreds of police and sought tighter control of the courts since a corruption inquiry burst into the open last month, a scandal he has cast as an attempted "judicial coup" meant to undermine him ahead of elections.
The purge extended to the banking and telecoms regulators as well as state TV over the weekend, with dozens of executives fired in moves that appeared to broaden the backlash.
Erdogan, who has mockingly dismissed expressions of concern from the EU, is due to hold talks from Tuesday with top officials including European Commission President Jose Manuel Barroso.
But the backdrop for his first trip to Brussels in five years is not the one that his aides might have hoped for.
"Erdogan's visit will have its challenges," said one official in his office, noting that the visit had been planned long before the corruption scandal erupted.
Ankara began negotiations to join the EU in 2005, 18 years after applying. But a series of political obstacles, notably over the divided island of Cyprus, and resistance to Turkish membership in Germany and France, have slowed progress.
Both sides are likely to make grand statements about the importance of reform and commitment to Turkish accession. But in private, officials say the developments of recent weeks mark a considerable setback in their relationship.
"This has chilled the atmosphere to a significant extent," one EU source told Reuters, describing Erdogan's reaction to the graft scandal as a "cold shower" for relations with the bloc.
A draft bill from Erdogan's ruling AK Party which would give government greater control over the appointment of judges and prosecutors, has raised alarm in Brussels.
Erdogan's supporters say the reforms will bolster, not weaken, the independence of the courts by curbing the power of Fethullah Gulen, a U.S.-based cleric and former ally who wields influence among the police and judiciary.
"We will continue with this step we have taken on the changes to the law ... Hopefully our friends will get this through parliament without delay," the prime minister told reporters in Ankara before leaving for Belgium.
Erdogan's visit had been meant to build on positive momentum after the start of a new round of EU membership talks in November, the first in more than three years. The discussions had been delayed by EU states in protest over a Turkish crackdown on anti-government demonstrations last summer.
Now Erdogan's critics say his response to the corruption probe is further evidence of the authoritarian tendencies of a man long held up by the West as a potential model of democratic leadership in the Muslim world.
"I think this visit will confirm the growing distance between Turkey and the EU," said Fadi Hakura, Turkey analyst at British think-tank Chatham House.
"The accession process is clearly comatose, is clearly stagnant and there is little trust between the Turkish government and EU."
Some in western Europe fear Turkish membership would widen the EU's borders too far, to the fringes of Iran, Iraq and Syria. Erdogan has repeatedly criticised the slow progress of the accession process and opposition from some EU members.
But his office stressed he would use his visit to Brussels to push for full membership.
"This visit is a sign that Turkey has not given up on the EU," the official in his office said.
"It is unjust to show Turkey as the reason for relations not going as intended ... Turkey is continuing to make reforms in every area and its economy is very strong. In this environment there is no benefit for anyone in halting Turkey any longer." (Additional reporting by Tulay Karadeniz in Ankara, Daren Butler and Ayla Jean Yackley in Istanbul; Writing by Nick Tattersall; Editing by Mark Trevelyan)