ISTANBUL (Reuters) - Turkey detained dozens of energy and education ministry staff on Tuesday in an investigation targeting the network of a U.S.-based cleric whom Ankara accuses of orchestrating last July’s attempted coup, state media said.

A picture of Turkish President Tayyip Erdogan is seen through Turkish national flags ahead of the constitutional referendum in Istanbul, Turkey, April 14, 2017. REUTERS/Alkis Konstantinidis

Some 50,000 people have been formally arrested in court cases targeting supporters of cleric Fethullah Gulen. President Tayyip Erdogan, who is meeting his U.S. counterpart Donald Trump in Washington on Tuesday, is seeking Gulen’s extradition.

Arrest warrants were issued for 60 energy ministry-linked workers and 25 education ministry staff and some 40 have already been detained, state-run Anadolu news agency reported. Many of them had previously been dismissed from their posts.

Anadolu said the suspects were believed to have been users of Bylock, an encrypted messaging app the government says was used by Gulen’s followers.

The arrest warrants came after a court on Monday jailed opposition newspaper Cumhuriyet’s online editor pending trial on a charge of spreading terrorist propaganda, the paper said.

Editor Oguz Guven joined a dozen journalists from Cumhuriyet, long a pillar of the secularist establishment, who are already in jail facing sentences of up to 43 years in prison, accused of supporting Gulen’s network.

Mass detentions were initially supported by many Turks and authorities say the measures are justified by the gravity of last July’s attempted coup, in which rogue troops commandeered warplanes to bomb parliament and used tanks to kill 240 people.

But criticism has mounted as the arrests widened, with relatives of many of those detained or sacked denying their involvement in the coup and calling them victims of a purge.

“NEW AUTHORITARIANISM”

A total of some 150,000 people, mainly civil servants, security personnel and academics have been suspended or sacked as part of a related crackdown.

“I fear for the Turkish people as they enter this new stage of authoritarianism,” Gulen said in a Washington Post article published to coincide with Erdogan’s White House meeting. He has denied any role in what he called the “deplorable coup attempt”.

Erdogan accuses Gulen, a former ally of the Islamist-rooted ruling AK Party, of infiltrating Turkish institutions to establish a ‘parallel state’.

In an article in Foreign Policy magazine calling for the cleric’s extradition, Turkish Foreign Minister Mevlut Cavusoglu said Gulen and his network represented a grave and imminent threat to Turkey’s national security and constitutional order.

Anadolu news agency said the investigation into Cumhuriyet’s Guven was focused on a story referring to the death in a road accident of a state prosecutor handling a case targeting Gulen’s network.

The headline said a “truck mowed down” the prosecutor who prepared the first indictment against the Gulenist Terror Organization (FETO), as Ankara refers to Gulen’s network. The cleric denies any involvement in the coup attempt.

Guven was initially detained on Friday on suspicion of trying to discredit those investigating Gulen’s network and Anadolu said the court ruled that the headline was an allusion to what would happen to those who investigated Gulen.

Cumhuriyet said the Tweet with that headline was posted by mistake and was removed 55 seconds later and replaced with a new headline saying the prosecutor had “died awfully in a truck accident”.

An indictment accusing the Cumhuriyet journalists previously jailed said the paper had been “taken over” by Gulen’s network and used to “veil the actions of terrorist groups”.

Turkey has closed more than 130 media outlets, raising concerns among Western allies about deteriorating rights and freedoms.