Chinese cryptocurrency entrepreneur Justin Sun speaks at a financial forum in Beijing, China November 4, 2015. Picture taken November 4, 2015. REUTERS/Stringer/ File Photo

By Elizabeth Howcroft and Lawrence Delevingne

(Reuters) -Justin Sun, one of the biggest known backers of President Donald Trump's World Liberty Financial crypto venture, said on Friday that his tokens connected to the project had been frozen, without giving further details.

Sun had spent at least $75 million on World Liberty Financial tokens, known as $WLFI, according to his posts on X. The tokens became publicly tradable on Monday and fell in value.

In a post on X addressed to "the World Liberty Financials team," Sun said: "during the course of operations, my tokens were unreasonably frozen" and asked the team to unlock them.

China-born crypto entrepreneur Sun did not specify what the operations were, how many tokens were frozen or who had frozen them.

The public comments by Sun were a reminder of the complexities of the business ties behind the Trump family's growing fortune from crypto ventures. This year, Eric Trump - the president's second-oldest son - and others at World Liberty have spoken onstage with Sun at major crypto events in Dubai and Hong Kong, and frequently posted on X.com praising each other and their respective crypto projects.

Sun is the second-largest known investor of World Liberty, and his early buy into the firm last year of $30 million matched the amount the company said it needed to jumpstart operations. Sun later said his investment totalled $75 million. Sun is also an adviser to World Liberty, and has used his crypto platforms to boost its flagship offering, stablecoin USD1.

The Trump family stake in World Liberty has made them hundreds of millions of dollars through their cut of token sales. Those riches have come at a time when Donald Trump has publicly backed the crypto industry, giving rise to broad criticisms of conflict of interest given that some of the family's business partners have in the past faced regulatory actions by the government that Trump now heads.

The U.S. Securities and Exchange Commission under the Trump administration, for example, has been exploring a resolution to its civil fraud case against Sun, Reuters reported in February.

Representatives for World Liberty Financial did not respond to a request for comment. A spokesperson for Sun's crypto firm, Tron, said in a statement to Reuters that "Justin and the WLFI team are in active communication about this matter."

Later on Friday, Sun signalled a change in tack, posting that he planned to buy $10 million of World Liberty tokens, and an additional $10 million in a separate, publicly traded U.S. stock that invests in World Liberty tokens.

Blockchain data shows that the World Liberty Financial "guardian address" on Thursday blacklisted a wallet owned by Sun which holds around 545 million of the tokens, according to Nicolai Sondergaard, research analyst at Nansen. This means that the tokens cannot be transferred out of that wallet.

Before being blacklisted, Sun transferred 50 million of the tokens to another address, the Nansen analyst said.

World Liberty had previously said that early investors would be able to sell up to 20% of their token holdings.

The tokens were trading at around 18 cents on Friday, according to CoinGecko, having initially traded above 30 cents at their debut.

(Reporting by Elizabeth Howcroft in Paris and Lawrence Delevingne in Boston, Editing by Elisa Martinuzzi, Sharon Singleton, Tom Lasseter and Matthew Lewis)