Turkish authorities on Tuesday detained the local chair of Amnesty International for suspected links to the network of the Muslim cleric Ankara blames for last year's failed coup, the rights group said.

Police detained Taner Kilic and 22 other lawyers in the Aegean coastal province of Izmir on suspicion of ties to the movement of US-based cleric Fethullah Gulen, it said, citing a detention order.

Since the July coup attempt, authorities have arrested 50,000 people and sacked or suspended 150,000, including soldiers, police, teachers and public servants, over alleged links with terrorist groups.

"Taner Kilic has a long and distinguished record of defending exactly the kind of freedoms that the Turkish authorities are now intent on trampling," said Salil Shetty, Amnesty's secretary general.

Turkish authorities were not immediately available for comment. Officials say the crackdown is necessary due to the gravity of the coup attempt, in which more than 240 people were killed.

Kilic was detained by police at his home in Izmir early on Tuesday before being taken to his office, Amnesty said. Both properties were searched and he remains in police custody.

His detention did not appear to be connected to his work with the rights group, nor did it appear to specifically target the organisation, Amnesty said. It was unclear why he was suspected of having links to Gulen's network, it said.

Gulen, who has lived in self-imposed exile in Pennsylvania since 1999, has denied involvement in the coup and condemned it. Critics in Turkey and abroad say President Tayyip Erdogan is using the coup as a pretext to muzzle dissent and purge opponents.

Turkey's interior ministry said on Monday it would strip citizenship from 130 people suspected of militant links, including Gulen, unless they return to Turkey within three months.