ANKARA (Reuters) - Turkey’s main opposition called for the resignation of Prime Minister Binali Yildirim on Wednesday, saying that reports his sons owned offshore companies amounted to a breach of ethics.

FILE PHOTO - Turkish Prime Minister Binali Yildirim attends a press briefing with his Vietnamese counterpart Nguyen Xuan Phuc (not pictured) at the Government Office in Hanoi, Vietnam August 23, 2017. REUTERS/Kham

Yildirim’s two sons are shown as the owners of two Malta-based companies, according to the so-called “Paradise Papers”, a series of leaked documents of offshore records that relate to global assets of wealthy individuals.

The spokesman for the main opposition Republican People’s Party (CHP), Bulent Tezcan, said that such offshore companies deprived Turkey of much-needed tax revenue.

“This is not a crime from a legal standpoint, that is a different argument, but it is wrong morally. Does your country need money? Yes, it does,” he said. “The first and only thing that the prime minister needs to do, now that this has surfaced, is to resign.”

The CHP and the pro-Kurdish HDP together submitted a motion to the parliament to investigate those named in the Paradise Papers, although it is unlikely to gain much traction in a legislature dominated by Yildirim’s ruling AKP.

Yildirim has said his sons, who are involved in the shipping industry, were not guilty of any wrongdoing.

“Shipping is a global business. They do business all over the globe, so they have companies and contacts all over the world,” he told reporters before departing for the United States on an official visit on Tuesday.

He invited critics to open a financial or legal investigation, and said it was “unacceptable” to accuse innocent people of wrongdoing.

He also showed reporters a certificate given to his family-owned company, showing it as one of the firms that paid the most in tax in Istanbul.

The Paradise Papers, which were obtained by Germany’s Sueddeutsche Zeitung and shared with the International Consortium of Investigative Journalists (ICIJ) and some media outlets, relate to the investments of individuals from U.S. Commerce Secretary Wilbur Ross to Britain’s Queen Elizabeth.

Reuters has not independently verified them.