Turkish President Tayyip Erdogan (Source: AP Photo/Jean-Francois Badias)

ISTANBUL (Reuters)—Turkey has effectively written a “blank check” to security services to torture people detained after a failed military coup attempt, a U.S.-based rights group said on Tuesday, citing accusations of beatings, sleep deprivation and sexual abuse.

A report by Human Rights Watch (HRW) said a “climate of fear” had prevailed since July’s failed coup against President Recep Tayyip Erdogan and the arrest of thousands under a State of Emergency. It identified more than a dozen cases raised in interviews with lawyers, activists, former detainees and others.

A Turkish official said the Justice Ministry would respond to the report later in the day; but Ankara has repeatedly denied accusations of torture and said the post-coup crackdown was needed to stabilize a NATO state facing threats from Kurdish militants as well as wars in neighboring Iraq and Syria.

Hugh Williamson, Europe and Central Asia director at HRW, said in a statement it “would be tragic if two hastily passed emergency decrees end up undermining the progress Turkey made to combat torture.”

“By removing safeguards against torture, the Turkish government effectively wrote a blank check to law enforcement agencies to torture and mistreat detainees as they like,” he said.

Erdogan reined in police use of torture especially in the largely Kurdish southeast, seat of a militant rebellion, when he first came to power in 2002. But the battle with Kurdish militants has become fiercer since the breakdown of a ceasefire last year and drawn accusations of rights abuses.

HRW said it had uncovered allegations that police had used methods including sleep deprivation, severe beatings, sexual abuse and the threat of rape since the failed coup. Cases were not limited to possible putschists, but also involved detainees suspected of links to Kurdish militant and leftist groups.

Turkey has arrested more than 35,000 people, detained thousands more and sacked over 100,000 people over their suspected links with Fethullah Gulen, a U.S.-based cleric blamed for orchestrating the coup attempt. Gulen denies the charge.

The government says the widescale crackdown is justified by the gravity of the threat to the state on July 15, when rogue soldiers commandeered tanks and fighters jets, bombing parliament and killing more than 240 people.

Erdogan declared a state of emergency days after the failed putsch, allowing him and the cabinet to bypass parliament in enacting new laws and to limit or suspend rights and freedoms as they deem necessary.