ANKARA, Turkey (AP) — Turkish media say a prominent businessman and rights activist has been detained for questioning by police.

Hurriyet newspaper and other media say Osman Kavala was detained late Wednesday at Istanbul's main airport upon returning from a city in southern Turkey. The reason was not known.

The government initiated a massive crackdown following last year's failed military coup that has resulted in 50,000 arrests and the dismissals of more than 110,000 government workers.

The initial targets were suspected of links to U.S.-based Muslim cleric Fethullah Gulen, who denies Turkey's accusation of heading the coup. But critics say the crackdown has been extended to target journalists, academics and political opponents of the government.