The document shows an agreement signed by Thailand's Wi Holding and Macau's China Kingdom Group this week outlining plans to issue virtual tokens that represent equity in the project over the next six to 12 months.

Wi Holding did not respond to a request for comment. China Kingdom Group could not be reached for comment.

The deal comes just three weeks after China banned the practice of raising funds through launches of token-based digital currencies. ICOs were targeted after they fuelled a rapid ascent in the value of crypto currencies this year that has triggered fears of a bubble.

Chakrit Ahmad, chief executive of Wi Holding, said on CNBC this week that the fundraising would not be affected by China's ban as tokens were being issued in Hong Kong, which has not banned ICOs.

Tony Tong, founder of cryptocurrency investment company Pacific Financial Services, had seen the document and said Wan Kuok-koi, chairman of Macau's World Hongmen History and Cultural Association, was a co-investor in the ICO.

Wan, whose nickname in Macau is "Broken Tooth", was released from a Macau prison in 2012 after serving 14 years for attempted murder, loan sharking and money laundering.

Wan was pictured in the company document reviewed by Reuters holding the agreement. He could not be reached for comment.

Separately, Milos Andric, the chairman of Norwegian maritime design firm Brova Idea, told Reuters his company had been contracted to construct an eco-friendly floating casino hotel in China's southern territory of Macau that would be sent to the former Portuguese colony in 2020.

Andric said his company was in the process of conducting engineering for the floating project.

He declined to reveal the identity of his client, citing confidentiality reasons, although a Brova company video seen by Reuters showed its partners as Wi Holding and China Kingdom Company together with a company called Dragon ICO.

The Hong Kong Monetary Authority said it could not comment on individual cases, but said investors needed to understand that a cryptocurrency trading platform "may be unregulated and located overseas, so investors may risk losing the entire investment if one ceases operations."

Macau's monetary authority told Reuters it had reminded banks and payment institutions in Macau on September 20 not to participate in or provide directly or indirectly any financial services for related Bitcoin activities.

The ICO would be the largest such offering to date when compared with past transactions listed on research site Cointelegraph. However, virtual currency investors remain sceptical about the prospects of such a deal being completed.

Leonhard Weese, president of the Hong Kong Bitcoin Association, said the ICO space was becoming exuberant and questioned the fundraising for the floating casino. He said such an offer was equivalent to about one percent of Bitcoin supply and, in terms of relative market impact, compared it to buying 1,800 tons of gold.

(Reporting by Farah Master; Additional reporting by Anne Marie Roantree; Editing by Sam Holmes, Greg Mahlich)

By Farah Master