George Soros’s Open Society Foundation will cease all activities in Turkey after the billionaire investor was singled out by President Recep Tayyip Erdogan.

The Açık Toplum Vakfı said it would seek to legally wind up its operations because the “intensification of baseless claims and unrestrained speculation in the media had made it impossible for the Foundation to continue its operations”.

In a speech last week Mr Erdogan alleged Mr Soros was funding a campaign to release Osman Kavala, a businessman in custody since last year on charges of conspiring to topple the government during mass protests in 2013.

“Behind [Kavala] is the famous Hungarian Jew, Soros,” Mr Erdogan said in a speech to local government leaders on Wednesday.

“This is a man with an abundance of money who assigns people to divide nations and shatter them.”

Following his remarks a number of newspapers close to Turkey’s governing party claimed Mr Soros had ilictly used the Foundation to channel overseas funds in support of anti-government activities within Turkey.

But the Foundation’s Turkish branch said in its statement on Monday that all its foreign donations had been reported to and approved by the relevant state-run agency.

The same agency detailed the final destination of those funds in its annual report every June, the Foundation added.