Turkish businessman among four arrested in coup probe

ANKARA, July 5 (Reuters) - Four out of 21 prominent Turks detained under a police investigation into coup allegations have been formally arrested, including a leading businessman, Turkish media said on Saturday.

The chairman of Ankara's Chamber of Commerce Sinan Aygun was among the four, the state-run Anatolian news agency said. Aygun is a vocal critic of the ruling AK Party government.

Five others, including the chief editor of a newspaper, were released on Friday but barred from leaving the country while the case continued, Anatolian said.

There was no official word on Saturday on the rest, who include two retired senior generals, journalists and politicians.

They were detained on Tuesday, hours before the first hearing in a case which could lead to the AK Party being banned if it is convicted of trying to introduce Islamic rule. Turkish media said those detained were suspected of being members of a shadowy, ultra-nationalist, hardline secularist group known as Ergenekon, which was already under investigation.

A secret plan, including launching illegal protests on July 7 across 40 provinces, assassinations and clashes with security forces, was seized during Tuesday's swoop, media said.

The prosecutor was not immediately available and Istanbul police declined comment.

Dozens of people had already been detained for suspected links to the Ergenekon group, including retired army officers.

The military -- which has repeatedly criticised the government and considers itself the guardian of Turkey's secular system -- has denied any links to the group.

The high-profile arrests and start of the case to close the party hit Turkish stock prices and the lira currency on Tuesday. The markets later rebounded thanks to foreign cash inflows. (Reporting by Selcuk Gokoluk; editing by Philippa Fletcher)