ANKARA, Turkey (AP) — Turkish opposition parties on Monday filed legal complaints to press Turkish prosecutors into investigating corruption allegations made by a fugitive mafia boss against people close to President Recep Tayyip Erdogan’s ruling party.

In a series of tweets over the weekend, Sedat Peker — a crime boss-turned-whistleblower — accused the former head of the Turkish Capital Markets Board, a ruling party legislator, a presidential adviser and others of being part of a network allegedly seeking bribes from companies trading on the stock market.

Peker alleged that members of the group sought bribes from a businesswoman in the guise of “consultancy fees,” to resolve a problem faced by her company. The businesswoman confirmed the allegations to the Halk TV news channel on Saturday.

The mafia boss further claimed that Serhat Albayrak — the head of the pro-government Turkuvaz Media group and the brother of Erdogan’s son-in-law, Berat Albayarak — coordinated the alleged bribery scheme. Albayrak's lawyer denied the allegation and said he would take legal action against the “completely untrue” accusations.

Other officials have also denied the claims.

On Monday, at least five opposition parties, including the main opposition Republican Peoples Party, or CHP, filed criminal complaints demanding that the judiciary — which they accuse of being subservient to Erdogan’s nationalist government — take action over the allegations.

“We know that the judiciary is currently in the service of the government,” said Mustafa Yeneroglu of the opposition Democracy and Progress Party, or DEVA. “However, we will file a criminal complaint ... in order for it to go down in history. One day, there will be responsible prosecutors who will go after these disgraces.”

Peker, a 51-year-old fugitive crime boss, once openly supported Erdogan’s Justice and Development Party. He became a social media phenomenon last year after he posted a series of videos from his stated base in the United Arab Emirates making scandalous accusations against Turkish political figures.

More recently, he has been making corruption allegations through his Twitter account, after he was reportedly advised to stop recording videos for security reasons.