By Daren Butler and Orhan Coskun

ISTANBUL/ANKARA (Reuters) - Turkish special forces backed by helicopters, drones and the navy hunted a remaining group of commandos thought to have tried to capture or kill President Tayyip Erdogan during a failed coup, as a crackdown on suspected plotters widened on Tuesday.

More than 1,000 members of the security forces were involved in the manhunt for the 11 rogue soldiers in the hills around the Mediterranean coastal resort of Marmaris, where Erdogan was holidaying on the night of the coup attempt, officials said.

Erdogan and the government accuse U.S.-based Muslim cleric Fethullah Gulen of orchestrating the attempted power grab and have launched a crackdown on his suspected followers. More than 60,000 soldiers, police, judges and civil servants have been arrested, suspended or put under investigation.

The religious affairs directorate removed another 620 staff including preachers and instructors in the Koran on Tuesday, bringing to more than 1,100 the number of people it has purged since the July 15 coup attempt.

Foreign Minister Mevlut Cavusoglu said two Turkish ambassadors, currently in Ankara, had also been removed. Former Istanbul governor Huseyin Avni Mutlu was detained and his house searched.

"There is no institution which this structure has not infiltrated," Erdogan's son-in-law, Energy Minister Berat Albayrak, said in a televised interview, referring to Gulen's network of followers.

"Every institution is being assessed and will be assessed," he said. The response from the Turkish authorities would, he said, be just and not amount to a witch-hunt.

The coup attempt raised particular questions about the air force, some of whose senior members were deeply involved, and could lead to the re-investigation of past incidents including the downing by the Turkish military of a Russian warplane near the Syrian border last year, Albayrak said.

The incident provoked Russian trade sanctions but there are signs of rapprochement, with Turkey thanking Moscow for its solid support during the abortive putsch. By contrast it has frosty ties with Europe, which has criticized the post-coup crackdown, and with the United States, which it has urged to extradite Gulen.

Albayrak made the comments as the highest-level Turkish delegation since the downing of the jet visited Moscow and officials announced a planned meeting between Erdogan and Russian President Vladimir Putin next month.

"Erdogan will be eager to send a message to Washington and EU capitals that Turkey has other options," said Tim Ash, a strategist at Nomura and a veteran Turkey watcher.

The Turkish parliament set up on Tuesday a commission to investigate the coup attempt, with the backing of all political parties. It will also examine the allegations that the Gulen movement infiltrated the government and instigated the coup attempt.

Justice Minister Bekir Bozdag said suspects were now being questioned. "Those testimonies will give us a lot of information about the Gulen movement's influence within Turkey," he said during the commission's discussions.

MOST TURKS BLAME GULEN

Gulen, who has lived in self-imposed exile in the United States since 1999, denies involvement and says the coup may have been orchestrated by Erdogan himself to justify a crackdown, a suggestion the president has roundly condemned.

In an op-ed in the New York Times, Gulen wrote that if members of his "Hizmet" (Service) network had been involved in the attempted coup they had betrayed his ideals, saying Erdogan's accusations revealed "his systematic and dangerous drive towards one-man rule".

Almost two thirds of Turks believe Gulen was behind the coup attempt, according to a poll released on Tuesday. The Andy-Ar survey showed nearly 4 percent blamed the United States or foreign powers and barely 2 percent blamed Erdogan.

On July 15 rogue soldiers commandeered fighters jets, helicopters and tanks to close bridges and try to seize airports. They bombed parliament, police headquarters and other key buildings in their bid for power. At least 246 people were killed, many of them civilians, and 2,000 wounded.

Around a third of Turkey's roughly 360 serving generals have been detained since the abortive coup, more than 100 of them already charged pending trial.

Two Turkish generals based in Afghanistan were detained in Dubai, a Turkish official said on Tuesday, naming them as Major-General Cahit Bakir, a commander of Turkish forces serving in the international NATO-led security force in Afghanistan, and Brigadier Sener Topuc, who oversees education and aid in the country.

MANHUNT

The 11 soldiers being hunted in Marmaris were among a group of commandos who attacked a hotel where Erdogan had been staying. Seven others were detained at a police checkpoint on Monday.

As the coup unfolded, Erdogan said the plotters had tried to attack him in Marmaris, bombing places where he had been shortly after he left. He "evaded death by minutes", an official close to him said at the time.

"It was an assassination attempt against Erdogan and this is being taken very seriously ... Searches are continuing in Marmaris and the surrounding areas with around 1,000 members of the security forces," another official said on Tuesday.

"The searches will continue uninterrupted until these people are found."

Weapons, hand grenades and ammunition have been seized in the countryside around Marmaris in an operation based on information from detained soldiers, said Amir Cicek, governor of Mugla province where Marmaris is located.

Special forces police, commandos, the coast guard and the navy were all involved, Cicek said in a statement.

The scale of the arrests and suspensions following the coup attempt have raised concerns among rights groups and Western countries, which fear that Erdogan is capitalizing on it to muzzle dissent and remove opponents across the board.

Erdogan has declared a state of emergency, which allows him to sign new laws without prior parliamentary approval and limit rights as he deems necessary. In his first such decree, Erdogan ordered the closure of thousands of private schools, charities and foundations with suspected links to Gulen.

The measure went "well beyond the legitimate aim of promoting accountability for the bloody July 15 coup attempt," said Emma Sinclair-Webb, Turkey director at Human Rights Watch.

"It is an unvarnished move for an arbitrary, mass and permanent purge of the civil service, prosecutors and judges, and to close down private institutions and associations without evidence, justification or due process," she said.

Turkey wants the United States to extradite the cleric, a call supported on Tuesday by Kemal Kilicdaroglu, the leader of Turkey's main secularist opposition, but Washington has said it will do so only if there is clear evidence of wrongdoing.

In a sign of Washington's concerns about the security situation, the U.S. Embassy in Ankara said on Tuesday employees' family members had been authorized to leave voluntarily, citing a possible "increase in police or military activities and restrictions on movement" by the Turkish authorities.

(Additional reporting by Humeyra Pamuk, Ayla Jean Yackley and Gareth Jones in Istanbul, Ercan Gurses and Gulsen Solaker in Ankara, Denis Pinchuk in Moscow; writing by Nick Tattersall and Seda Sezer; editing by Gareth Jones, Peter Graff and David Stamp)