A dispute over the future of the Woodstock 50 festival has spiralled into a court fight, with organisers suing a former investor that tried to call off the anniversary show.
Woodstock 50 organisers are accusing ex-partner Dentsu Aegis Network of verbally and financially sabotaging the big-name event that organisers insist will still unfold in New York in August.
Denstu Aegis has pulled out of the concert and raised concerns about safety.
The two sides are clashing over nearly $US18 million ($A26 million) that the organisers say their ex-investor withdrew from the festival bank account.
"Dentsu's actions have caused a worldwide uproar over its efforts to kill the festival's commemoration of one of the most iconic cultural events of the 20th century," Woodstock 50 LLC's lawyer, Marc Kasowitz, wrote in a lawsuit filed in Manhattan this week.
The suit seeks the return of the bank account money. Woodstock 50 also wants an order barring Dentsu, an international marketing company, from talking about the festival with the media, performers or others.
A Manhattan judge on Thursday temporarily granted the gag order, at least until a hearing set for Monday, court records show.
There were no immediate responses to requests for comment sent Thursday to London-based Dentsu Aegis and its Japanese parent, Dentsu.
More than 75 performers have been announced, including Jay-Z, Dead & Company and the Killers as headliners.
Behind the scenes, trouble began brewing between the organisers and their chief investor about six weeks ago, according to the lawsuit.
It says Dentsu started to slow-walk payments and accused Woodstock 50 of violating their agreement - allegations that the lawsuit denies without detailing.
Then, on April 29, Dentsu announced it was cancelling the event.
"We don't believe the production of the festival can be executed as an event worthy of the Woodstock brand name while also ensuring the health and safety of the artists, partners and attendees," the company said in a statement at the time.
Hours later, Woodstock 50 co-founder Michael Lang and Woodstock LLC said the concert remained a go.
The original Woodstock concert in 1969 was held about 185km southeast of Watkins Glen on a farm in Bethel, New York.
It's now run by The Bethel Woods Center for the Arts, which has its own anniversary concert planned with performances by Ringo Starr, John Fogerty and Santana.
Australian Associated Press