By Jonny Hogg
ANKARA (Reuters) - The Turkish government has canceled the passport of ally-turned-foe Fethullah Gulen, local media reported on Tuesday, the latest salvo in a bitter feud between the U.S.-based Muslim cleric and President Tayyip Erdogan.
Erdogan and his ruling AK Party accuse Gulen and his supporters of seeking to establish a "parallel state" in Turkey and of orchestrating a corruption investigation in 2013 which briefly threatened to engulf the government.
Gulen, who denies the accusations, stepped up his own criticism of Erdogan, saying he was leading Turkey "toward totalitarianism".
CNN Turk said on its website that Turkey had informed U.S. officials on January 28 that it was revoking Gulen's passport because it was issued based on a "false statement". Gulen has lived in self-imposed exile in Pennsylvania since 1999.
A Turkish foreign ministry official said he could not confirm the media reports.
The move could bring Ankara a step closer to issuing a formal extradition request for Gulen. Washington is expected to reject such a demand, further fraying bilateral ties already strained over regional policy and U.S. concerns over what some see as Erdogan's increasing authoritarianism.
Erdogan has already called for Gulen to be deported. In December a court issued an arrest warrant for the cleric, who had been a close ally of Erdogan's Islamist-rooted party for many years after it came to power in 2002.
After the graft allegations emerged in 2013, however, Erdogan, then prime minister, purged Turkey's state apparatus, reassigning thousands of police and hundreds of judges and prosecutors deemed loyal to Gulen.
Turkish authorities have also conducted raids against media organizations seen as close to Gulen, triggering criticism from rights groups and the European Union, which Turkey still aspires to join.
Hidayet Karaca, head of the Samanyolu broadcaster who has been jailed since December, said on Tuesday the case against Gulen and senior media executives was politically motivated.
"The police raids and arrests have become part of a strategy by the AKP government to silence the free press … It's no longer possible to discuss judicial independence in Turkey," Karaca said in a written response to questions from Reuters submitted through his lawyers.
In an op-ed published on Tuesday in the New York Times entitled 'Turkey's Eroding Democracy', Gulen accused Erdogan -- who remains popular in Turkey -- of using his electoral successes to ignore the constitution and suppress dissent.
"By viewing every critical voice as an enemy — or worse, a traitor — they are leading the country toward totalitarianism," he wrote.
(Additional reporting by Ayla Jean Yackley; Editing by Humeyra Pamuk and Gareth Jones)