Turkish authorities on Saturday detained a key aide to Fethullah Gulen, the US-based Muslim cleric Turkey blames for a failed military coup attempt.
Halis Hanci, described as Gulen's right-hand man, apparently entered Turkey two days before the abortive coup, a presidency official told reporters.
READ MORE: Fear grows as Turkey introduces state of emergency
Earlier on Saturday, Turkish authorities also detained a nephew of Gulen in connection with the coup attempt, the Anadolu state news agency reported.
Muhammed Sait Gulen was detained in the northeastern city of Erzurum and will be brought to the capital of Ankara for questioning.
Among possible charges that could be brought against him is membership of a "terrorist" organisation, the agency said, adding that he was also wanted over the leak of questions from the 2010 civil service exams.
It is the first time a relative of Gulen has been reported detained since the July 15 events. In May this year, another nephew of the former imam in self-imposed exile was detained in connection with schools run by the movement, according to a state media report at the time.
Pennsylvania-based Gulen is accused of "masterminding" the July 15 attempt to topple the government of President Recep Tayyip Erdogan through his movement - a claim he strongly denies. Turkey is seeking Gulen's extradition from the US.
Turkey has detained more than 13,000 people as part of a crackdown in response to a failed military coup, President Recep Tayyip Erdogan said late on Saturday, not long after the presidential guard became the latest target of the purge.
Of those detained, 6,000 have been placed under arrest.
Some 37,500 civil servants and police officers have so far been suspended, including many from the education ministry.
The rapid pace of arrests since the coup attempt has worried many of Turkey's Western allies, who say they see the country going down an increasingly authoritarian road.
Presidential guard disbanded
Earlier on Saturday, Erdogan issued a decree to close 2,341 institutions - including schools, charities, unions and medical centres - in the wake of the failed coup.
The decree, which local media noted as being the first taken under the powers of the recently declared state of emergency, also extends the legal time a person can be detained to 30 days.
Also on Saturday, Prime Minister Binali Yildirim said authorities would disband the elite presidential guard after detaining almost 300 of its members in the wake of the failed coup.
"There will no longer be a presidential guard. There is no purpose, there is no need," Yildirim said, speaking to A Haber channel.
The presidential guard is a regiment numbering up to 2,500 people, but at least 283 of its members had been detained after the attempted coup.
Source: Al Jazeera and agencies