Turkey has issued detention orders for 3,224 people over alleged links to last year's failed coup, local media reports.

More than 1,000 had already been detained by Turkish authorities, NTV said, accused of secretly infiltrating police forces across the country on behalf of a US-based cleric blamed by the government for last July's coup.

The nationwide sweep was one of the largest operations in months against suspected supporters of the cleric, Fethullah Gulen, a former ally of President Recep Tayyip Erdogan who is now accused by the government of trying to topple him by force.

Turkey's president Recep Erdogan wins referendum to greatly expand powers

Interior Minister Suleyman Soylu said the overnight crackdown targeted a Gulen network "that infiltrated our police force, called 'secret imams'.

"One thousand and nine secret imams have been detained so far in 72 provinces, and the operation is ongoing," he told reporters in Ankara.

In the aftermath of the failed July coup, authorities arrested 40,000 people and sacked or suspended 120,000 from a wide range of professions including soldiers, police, teachers and public servants, over alleged links with terrorist groups.

In pictures: Turkey coup attempt Show all 17 1 /17 In pictures: Turkey coup attempt In pictures: Turkey coup attempt Turkish President Erdogan attends the funeral service for victims of the thwarted coup in Istanbul at Fatih mosque on July 17, 2016 in Istanbul, Turkey Burak Kara/Getty Images In pictures: Turkey coup attempt Soldiers involved in the coup attempt surrender on Bosphorus bridge with their hands raised in Istanbul on 16 July, 2016 Gokhan Tan/Getty In pictures: Turkey coup attempt A civilian beats a soldier after troops involved in the coup surrendered on the Bosphorus Bridge in Istanbul, Turkey, 16 July, 2016 REUTERS/Murad Sezer In pictures: Turkey coup attempt Surrendered Turkish soldiers who were involved in the coup are beaten by a civilian Reuters In pictures: Turkey coup attempt Soliders involved in the coup attempt surrender on Bosphorus bridge Getty In pictures: Turkey coup attempt Supporters of Turkish President Recep Tayyip Erdogan wave flags as they capture a Turkish Army vehicle Getty In pictures: Turkey coup attempt People pose near a tank after troops involved in the coup surrendered on the Bosphorus Bridge in Istanbul, Turkey, 16 July, 2016 Reuters In pictures: Turkey coup attempt Turkish soldiers block Istanbul's Bosphorus Brigde Getty In pictures: Turkey coup attempt A Turkish military stands guard near the Taksim Square in Istanbul Reuters In pictures: Turkey coup attempt Pierre Crom/Twitter In pictures: Turkey coup attempt Turkish soldiers secure the area as supporters of Recep Tayyip Erdogan protest in Istanbul's Taksim square AP In pictures: Turkey coup attempt People demonstrate in front of the Republic Monument at the Taksim Square in Istanbul Murad Sezer/Reuters In pictures: Turkey coup attempt Turkish soldiers detain police officers during a security shutdown of the Bosphorus Bridge Reuters In pictures: Turkey coup attempt Turkish Army armoured personnel carriers in the main streets of Istanbul Getty In pictures: Turkey coup attempt Chaos reigned in Istanbul as tanks drove through the streets EPA/TOLGA BOZOGLU In pictures: Turkey coup attempt Turkish President Tayyip Erdogan speaks to media in the resort town of Marmaris Reuters In pictures: Turkey coup attempt Supporters of President Erdogan celebrate in Ankara following the suppression of the attempted coup Reuters

The latest detentions came 10 days after voters narrowly backed plans to expand Mr Erdogan's already wide powers in a referendum which opposition parties and European election observers said was marred by irregularities.

A leading European human rights body has placed Turkey on a watchlist over concerns about the functioning democratic institutions in the country.

The referendum bitterly divided Turkey.

Mr Erdogan's critics fear further drift into authoritarianism, with a leader they see as bent on eroding modern Turkey's democracy and secular foundations.

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The Turkish President argues strengthening the presidency will avert instability associated with coalition governments, at a time when Turkey faces multiple challenges including security threats from Islamist and Kurdish militants.

"In Turkey, there was an attempted coup with a goal of toppling the government and destroying the state," he said in an interview with Reuters.

"We are trying to cleanse members of FETO inside the armed forces, inside the judiciary and inside the police," he added, using an acronym for the label, Gulenist Terrorist Organisation, which the government has given to Mr Gulen's supporters.

The president compared the struggle against Mr Gulen with the state's battle against Isis and Kurdish PKK militants, who are designated terrorist organisations by Turkey, the European Union and the United States.

"We are going to keep up the fight in terms of democracy, fundamental rights and liberties, but at the same time we are going to keep up the fight against PKK, FETO and other terrorist organisations such as Daesh [Isis]," he said.