* Brings forward business update to May 21

* Hedge fund Muddy Waters: situation at firm is 'unprecedented'

* Trading on stock has been suspended since May 10

PARIS, May 19 (Reuters) - Solutions 30 said it will update shareholders about its business on Friday rather than next week as planned after France's financial regulator called on the technology services group to publish its audited 2020 results, while hedge fund Muddy Waters kept up pressure on the company.

Trading in shares of Solutions 30, headquartered in Luxembourg and listed in Paris, has been suspended since May 10, and the company had planned to issue an update on May 25.

The company published its fourth-quarter and 2020 results on April 28. But it said that while its supervisory board approved the results, they were still being audited. The company said it hoped to issue the audited results April 29 but missed the deadline.

Earlier this week, the French AMF regulator noted Solutions 30 had not published audited results and urged it to do so.

Solutions 30, which has a stock market value of around 1.1 billion euros ($1.4 billion), said in January that it had decided to file a defamation suit over criticism made by hedge fund Muddy Waters regarding its business practices.

Muddy Waters, which has a short position betting on a fall in Solutions 30's shares, described on Wednesday the situation at Solutions 30 as "unprecedented."

Muddy Waters added it had not been served notice of any defamation suit against it by Solutions 30.

Solutions 30 has more than 11,000 service engineers who handle tasks such as cable installations and general technical support, according to its website.

($1 = 0.8169 euros) (Reporting by Sudip Kar-Gupta; editing by Jason Neely and Cynthia Osterman)