The news comes just over a week after confirmation of a controversial merger between the PGA Tour and DP World Tour with Saudi Arabia's Public Investment Fund (PIF).

Monahan oversaw the deal which is aimed at ending the civil war caused in golf by the launch of LIV Golf, funded by the PIF.

He has faced widespread criticism since, including being branded a hypocrite as he spent months attacking LIV Golf before performing a dramatic U-turn with the merger.

"Jay Monahan informed the PGA Tour Policy Board that he is recuperating from a medical situation," a PGA statement said. 

"The Board fully supports Jay and appreciates everyone respecting his privacy."

Ron Price, the chief operating officer, and Tyler Dennis, the executive vice-president and President, will now lead day-to-day operations in Monahan's absence.

The PGA said this would ensure "seamless continuity".

"We will provide further updates as appropriate," it added. 

A new company following the merger is set to see Monahan act as chief executive and PIF governor Yasir Al-Rumayyan sit as chairman.

Monahan said the deal had taken seven weeks to agree but players have reacted furiously after not being involved in the discussions, with some calling for him to resign.

Many said they found out through media reports, phone messages or on social media.

Spain's world number two and Masters winner Jon Rahm said "a lot of players feel betrayal from management" while Australia's Open champion Cameron Smith said he thought the news was a "joke".

Clear details on the merger still remains unclear with England's US Open champion Matt Fitzpatrick saying that "nobody knows what's going on apart from about four people in the world".

"Are we signing with the PIF?" he said.

"Are we not signing with the PIF? 

"I've no idea."

An investigation into the merger has been launched by the United States Senate which has cited concerns over Saudi Arabia's "deeply disturbing human rights record".

The country has been frequently accused of sportswashing to distract from its policies.

Democratic Senator Richard Blumenthal said that "prior to this agreement, the PGA Tour was one of the loudest critics of LIV Golf's affiliation with Saudi Arabia".

Monahan previously referenced the September 11 terrorist attacks - when 15 of the 19 plane hijackers were from Saudi Arabia - when criticising players for leaving for LIV Golf.

A group representing victims' families said he now should be "ashamed" of his "hypocrisy and greed". 

Major champions who decided to defect to the LIV ranks for huge pay packets included Smith, Phil Mickelson, Dustin Johnson, Brooks Koepka, Patrick Reed and Sergio Garcia.

Tiger Woods, Rory McIlroy and Rahm were among big names who refused to switch over.

LIV golfers who were subsequently suspended by the PGA and DP World Tour will be able to re-apply for membership from the end of the 2023 season.