By Daren Butler and Ayla Jean Yackley
ISTANBUL (Reuters) - Turkish Prime Minister Tayyip Erdogan, expected to run for president in August, has signaled that he will intensify a purge of state institutions to curb the influence of an Islamic cleric he accuses of trying to topple him.
Erdogan used a speech on Sunday after a meeting of his ruling AK Party to make clear his battle with U.S.-based cleric Fethullah Gulen is far from over.
Thousands of police officers and hundreds of judges and prosecutors have been reassigned and senior officials in state institutions dismissed in what is widely seen as a move to stifle the influence of Gulen's Hizmet movement.
Erdogan accuses Gulen, who has many supporters in the police, judiciary and state bureaucracy, of orchestrating a corruption scandal to try to unseat him and of establishing a "parallel structure" within the state. He has called on the United States to extradite Gulen, who has lived in self-imposed exile in Pennsylvania since 1999.
Gulen denies plotting against the government.
Erdogan has said the final decision on his presidential candidacy may not come until mid-June, but he is due to hold a rally in Cologne, Germany, this month after regulatory changes made it easier for Turks abroad to vote.
Yasin Aktay, the AK Party's vice chairman in charge of foreign affairs, told reporters in Istanbul on Monday that an Erdogan presidency would be stronger than that of Abdullah Gul, who has played a more ceremonial role.
"The presidency of Tayyip Erdogan will never keep within the limits of a ceremonial (role). The authorities listed in the constitution now are very big," he said.
He said none of Gulen's followers would be removed from their posts simply for being members of the movement, but said if they were working within the bureaucracy and taking orders from elsewhere, they would be expelled.
"Now it's war. There's no way back," Aktay said.
Erdogan said at Sunday's meeting in the western province of Afyonkarahisar: "If transferring people who have betrayed this country from one post to another is a witch hunt, yes we will conduct a witch hunt.
"With the sensitivity of a surgeon, we will sterilize this dirty water mixed up in the milk, boiling it, identifying it down to the molecules," he said. His opening and closing remarks were broadcast on television.
The Hizmet ("Service") movement, with its global network of schools and influence within Turkey's civil service, was long an ally of Erdogan's conservative, Islamist-rooted government.
But relations descended into open hostility after December's corruption investigation emerged and led to the resignation of three cabinet ministers, posing what appeared to be the greatest threat to Erdogan's 11 years in office. That followed the biggest anti-government protests in decades against Erdogan's perceived authoritarianism last summer.
Since then, Erdogan's AK Party dominated local elections in March despite a slew of leaked recordings purporting to reveal government corruption, while prosecutors this month threw out graft allegations against 60 suspects, burying part of the scandal that had dogged his inner circle for months.
On Saturday, the prime minister heckled the head of the bar association, accusing him of rudeness for criticism of the government in a speech at a judicial ceremony before storming out of the hall.
Among the most recent reshuffles in the bureaucracy, the state-run stock exchange Borsa Istanbul dismissed three senior personnel last week. The regulatory Capital Markets Board dismissed three deputy chairmen and 11 other senior members in April in a move that one source said was government retaliation for the corruption investigation, and staff in the banking regulator and Finance Ministry have also been removed from posts.
Finance Minister Mehmet Simsek last week told a Financial Times conference in Istanbul: "If we feel some of these senior bureaucrats are associated with the so-called rogue state, of course we should move. There is nothing wrong with that."
Erdogan appealed directly to party members on Sunday to pass on information about suspected supporters of the group, saying:
"I say to you my dear friends: you will inform us who does what and where on this subject."
He said if the government did not take action: "We will be involved in treachery in this country."
(Additional reporting by Nick Tattersall; Writing by Daren Butler; Editing by Janet Lawrence)