Turkish Prime Minister Binali Yildirim announced that the United States has been given evidence of exiled opposition leader Fethullah Gulen's "involvement" in the failed coup, as he warned that further "criminal activity will be forcefully dealt with".

In an address on Tuesday before members of his party in parliament, Yildirim denounced the "despicable" and "cowardly" coup plotters, whom he said were being "directed by a cleric" from abroad, referring to Gulen.

"The power of the tank has not been able to overcome the power of the people," he said, adding that all those involved in the coup will be "severely punished".

Turks pessimistic about future after coup attempt

Yildirim did not say whether the evidence provided by the Turkish government to the US constitutes a formal extradition request.

But later on Tuesday, White House spokesman Josh Earnest said the Turkish government had filed materials in electronic form with the US government, which were in review.

Ankara had earlier demanded Washington hand Gulen over to Turkish authorities.

Gulen, who is resident in the US, has denied any involvement in the military plot to topple the government of President Recep Tayipp Erdogan, and hinted that the coup might have been staged to justify his arrest.

Yildirim's speech came as the government detains government workers, including police officers, members of the civil service and the judiciary.

Al Jazeera's Bernard Smith, reporting from Istanbul, said as many as 20,000 government employees have been detained, or are being pursued by the authorities, including 185 admirals and colonels, and 1,500 finance ministry officials.

Reuters also reported that 257 personnel from the prime minister's own office have also been removed from duty.

Turkey's Education Ministry on Tuesday suspended 15,200 personnel in connection with the failed coup, state media reported. Later, the High Education Board ordered the resignation of all 1,577 deans employed at all universities, TRT reported.

Turkey's religious directorate issued a statement on Tuesday, saying it would not offer religious funerary services, including funeral prayers, for soldiers involved in the failed coup attempt, except for those who had been "forcibly dragged" into the military actions attempting to overthrow the government.

'Serious alarm'

Yildirim said that the government will make a major announcement on Wednesday in response to the coup attempt.

He did not specify what action the government would take, but earlier on Tuesday, President Erdogan said he is ready to reinstate the death penalty.

"There is no time to rest," Yildirim said to cheers from party colleagues. "There is a group of people who are going to be punished."

A top United Nations human rights official urged Turkey to uphold the rule of law, and voiced "serious alarm" at the mass suspension of judges and prosecutors.

UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein also called for independent observers to visit places of detention in Turkey to check on conditions, and for detainees to have access to lawyers and their families.

"In the aftermath of such a traumatic experience, it is particularly crucial to ensure that human rights are not squandered in the name of security and in the rush to punish those perceived to be responsible," Zeid said in a statement.

"Reintroduction of the death penalty would be in breach of Turkey's obligations under international human rights law - a big step in the wrong direction," he said.

The European Union has also warned that Turkey's accession to the European Union would halted if the death penalty is reinstated.