Turkey's President Recep Tayyip Erdogan has extended the period in which suspects can be detained without charge to 30 days, an official statement says.
The statement also ordered the closure of more than 1,000 private schools and more than 1,200 associations.
It follows last week's failed coup attempt against Mr Erdogan and the subsequent declaration of a state of emergency.
Mr Erdogan has blamed the coup attempt on US-based cleric Fethullah Gulen.
Mr Gulen has denied any involvement.
The Turkish leader has said the state of emergency will allow the authorities to deal with the aftermath of the failed coup effectively, allowing them to restore order.
At least 60,000 state employees have been detained or suspended in an internationally criticised purge.
Education ministry officials, private school teachers and university heads of faculty together account for more than half the people targeted.
The schools and associations whose closures have now been ordered are suspected of having links to Mr Gulen, Turkey's state news agency Anadolu said.
Other institutions ordered to be shut down included 19 trade unions, 15 universities and 35 medical institutes, the agency said.
Human rights groups including Amnesty International warned Turkey against extending the period allowed for detention without charge, which previously stood at a maximum of four days.
Amnesty has said Mr Erdogan is going "well beyond what might be considered a legitimate response to the coup attempt".