Istanbul (AFP) - A Turkish court has remanded in custody seven people, including a top construction executive, on charges of financing President Tayyip Erdogan's foe, Muslim cleric Fethullah Gulen, state media said Friday.

The seven were detained Monday along with some 100 others in a fresh crackdown on the US-based preacher, who is accused by the Turkish government of running a "terror organisation" seeking to overthrow his former ally Erdogan.

The chairman of leading construction firm Dumankaya Insaat, Halit Dumankaya, was one of four remanded on a charge of "providing financing for a terror group", the Anatolia news agency said.

The other three are accused of "being members of an armed terror group", it said.

Founded in 1963, Dumankaya is one of Turkey's biggest property developers with a string of prestigious projects in Istanbul.

The company is also the shirt sponsor of top Istanbul football team Galatasaray, meaning its stars like Germany's Lukas Podolski or Wesley Sneijder of the Netherlands wear the firm's name on their kit.

Turkish prosecutors had issued arrest warrants for 140 people and at least 105 people were detained at the week's start. By Friday, all but the seven had been released, though 37 were subject to monitoring by judicial authorities.

But Anatolia said another 20 people including businessmen and lawyers had been arrested on Friday on suspicion of financing Gulen's group, with prosecutors issuing warrants for a further 30 suspects.

Ankara accuses Gulen of running what it calls the Fethullahaci Terror Organisation/Parallel State Structure (FeTO/PDY) and seeking to overthrow the legitimate Turkish authorities.

But his supporters decry the accusations as ridiculous, saying all he leads is a more informal group known as Hizmet (Service).