The association alleges the ATP has tried to pressure players into signing pre-prepared statements saying they had no prior knowledge of the legal action launched this week by the PTPA.

The union, which was co-founded by 24-time major winner Novak Djokovic, cited “anti-competitive practices and a blatant disregard for player welfare” in lawsuits filed on Tuesday.

Djokovic is not one of the players listed as a plaintiff in the official court documents, but said publicly at the Miami Open on Thursday that there are elements of the lawsuit with which he agrees, and some with which he does not.

The Serb went on to say: “I’ve seen some changes, but there are some fundamental changes that are still yet to be made and I really hope that all the governing bodies, including PTPA, will come together and solve these issues.”

The PTPA, “on behalf of the entire player population”, is taking action against the men’s ATP Tour, the women’s WTA Tour, the International Tennis Federation and the International Tennis Integrity Agency in the US, the UK and the European Union.

Australia’s Nick Kyrgios is the most high-profile player to be named as a plaintiff alongside the PTPA.

In papers filed late on Friday to the United States District Court in New York, lawyers for the PTPA asked Judge Margaret Garnett to issue an order which prevents all four defendants from communicating with players about their involvement in the process.

The motion accuses the ATP of threatening to reduce prize money and pension contributions to offset legal fees which it will accrue from fighting the case. It argues this constitutes “flagrant interference” with the jurisdiction of the court.

Friday’s motion also claims the ATP initiated a series of meetings and conversations at this week’s Miami Open and alleges “ATP officials have threatened players with adverse consequences for participating in this action”.

The ATP says prize money has increased by $70m (£54m) in the past five years, and can point to the $28.5m (£22m) of prize money available to emerging and lower-ranked players on the Challenger Tour this year.

The PTPA says an expedited decision, to prevent defendants communicating with players, is necessary so players can make “informed decisions about their participation in this case, and fully and freely pursue their legal rights without undue influence by the same parties who control their pay cheques and professional endeavour”.

In a statement released on Tuesday, the ATP said it “strongly rejects the premise of the PTPA’s claims”, declaring the case to be “entirely without merit” and promising to “vigorously defend” its position.

It accused the PTPA of having “consistently chosen division and distraction through misinformation over progress” and said the ATP “remains committed to working in the best interests of the game”.

The WTA said it will defend its position and said in a statement the legal action is “both regrettable and misguided”.

It added: “Contesting this baseless legal case will divert time, attention, and resources from our core mission, to the detriment of our players and the sport as a whole.”

An ATP spokesperson said: “We are aware of the request for an additional court order being sought by the PTPA and refute its assertions.

“At the heart of ATP is our commitment to players. As this is now a legal matter we have no further comment to make.”