The PGA Tour, DP World Tour and rival Saudi-backed LIV circuit, which had been involved in a bitter fight that split the sport, announced an agreement last week to merge and form one unified commercial entity.

The LIV Golf series is bankrolled by the Saudi Arabia Public Investment Fund. Critics have accused it of being a vehicle for the country to improve its reputation as it faces criticism of its human rights record.

“The PGA-LIV deal would make a U.S. organization complicit – and force American golfers and their fans to join this complicity – in the Saudi regime’s latest attempt to sanitize its abuses by pouring funds into major sports leagues," the senators wrote.

"The deal appears to have a substantial adverse impact on competition, violating several provisions of U.S. antitrust law, regardless of whether the deal is structured as a merger or some sort of joint venture,” they added.

The Democrats said in a letter to Attorney General Merrick Garland that the deal "deserves serious and urgent attention by U.S. antitrust agencies."

The PGA Tour did not immediately comment. LIV and the Justice Department declined to comment.

The department has been investigating the PGA Tour for trying to keep its players from defecting to LIV.

On Monday, Senator Richard Blumenthal asked the PGA Tour and LIV Golf for communications and records on their planned tie-up.

Much of the human rights-related backlash centres around the alleged involvement of the Saudi Arabian government in a multitude of human rights violations, including the murder of Washington Post journalist Jamal Khashoggi in 2018.