Allegations of cryptocurrency fraud are growing against multiple South Korean celebrities and popular YouTubers, with some denying their involvement and some admitting to having invested in the cryptocurrency.

Winnerz -- a Korean blockchain sports platform that operates several businesses including issuing cryptocurrency -- has been accused of running a coin scam after anonymous investors alleged that the company was issuing fake cryptocurrency, gathering investments and forbidding investors to take out their money.

The total amount that Winnerz has allegedly refused to return to investors is not known.

Winnerz is accused of using a fraud tactic in which celebrities are recruited to bolster the credibility of the cryptocurrency to attract investors. In this case, celebrities could either buy the coins themselves, merely help recruit more investors for a commission, or do both.

According to an anonymous online post, the case involving alleged 'Winnerz coin fraud' has been submitted to the National Police Agency on Feb. 5 after having been reported to the National Civil Service.

Korean comedian Na Sun-uk was accused of involvement in the coin fraud after a picture of him at Winnerz's year-end party was discovered on social media.

In response to the accusations, Na posted on his YouTube channel on Sunday that "the information reported in the media is untrue, and I participated in the gatherings shown in the photos once for a birthday party and once for a year-end party, due to the personal connections I have with the participating creators."

"Both meetings were brief dining occasions. I have no affiliation with Winnerz whatsoever, and I want to clarify that I have never engaged in any coin investments," said Na.

Kim Won-hoon and Cho Jin-se, the operators of popular YouTube channel Shortbox, which had 2.85 million subscribers as of Tuesday, also posted on their YouTube channel on Sunday that they "want to make it clear that there have been no business or financial discussions or transactions with Choi Seung-jung and other relevant parties mentioned concerning controversies surrounding Winnerz."

Choi Seung-jung is a Winnerz-related official who is alleged to have led a slew of coin frauds, including the GDG coin fraud and TYP coin fraud in which the investors were reportedly prevented from withdrawing their investments.

Kim and Cho were accused of participating in the Winnerz fraud after a picture of Kim taking a photo with Choi was recently found on social media.

Korean YouTuber Oh Byeong-min (widely known as Oking), who operates the OkingTV YouTube channel with 2 million subscribers as of Tuesday, admitted on Thursday that he had invested in Winnerz, after it was found that his name was listed on the Winnerz website as one of the directors of the company.

"I had invested in Winnerz. I have now announced my intention to withdraw the investment," said Oh in a video posted on Thursday.

"I have ceased all projects with Winnerz and have no plans to collaborate with Winnerz in the future," he said.

In response to the mounting fraud allegations, Winnerz announced on its website that "Winnerz is a blockchain technology-based sports platform company and it is a clearly established company with both online and offline operations."

"Winnerz has been transparent about its business and goals thus far, and we are announcing that these goals have been achieved within the publicly disclosed timelines. Additionally, Winnerz coin is listed on overseas exchanges," the post said.