The director of Tehran’s stock exchange Wednesday announced his resignation after cryptocurrency mining machines were uncovered at the offices of the organization.

After the news of the scandal broke on local media, Ali Sahraee told the ISNA news website “To offer an opportunity for more investigations about cryptocurrency mining at the stock exchange and to help the stability of the markets, I offered my resignation to the board of directors, which accepted it.”

Sahraee’s announcement contradicts news from the government’s official news website, IRNA, that said he was fired.

Around seven percent of the world’s cryptocurrencies are mined in Iran, most of it hidden from public view and illegally. The practice which requires thousands pf computers using large quantities of electricity has become controversial. Some Chinese entities are also engaged in the practice due to extremely cheap, subsidized electricity in Iran.

The stock exchange confirmed the operation of crypto machines on Wednesday and said there has not been full financial reporting, although the operation was meant to be for the stock exchange and not private. The board of directors confirmed that a number of machines were installed last year “for research purposes”.