Miami Marlins general manager Kim Ng, the first woman to be hired as boss of a men's professional sports team in North America, has stepped down from the post, the club confirmed on Monday.

Ng, who was hired in November 2020 and helped the Marlins return to the postseason in 2023, is reportedly leaving after a clash with team ownership.

US media reports said Ng had declined to take up an option to return in 2024 after objecting to a proposal to appoint someone above her as head of baseball operations.

"Although the club exercised its team option for her to return for the 2024 season, Kim has declined her mutual option," Marlins chairman and principal owner Bruce Sherman said in a statement.

"We thank Kim for her contributions during her time with our organization and wish her and her family well.

"We will immediately begin a thorough and extensive search for new leadership as we plan to continue to invest in the Marlins organization both on and off the field." 

The Marlins statement did not touch on the reported reasons for Ng's decision to step away.

However the 54-year-old executive confirmed in a statement to The Athletic website that she was not "aligned" with Sherman's vision for the team's future management structure.

"Last week, Bruce and I discussed his plan to reshape the baseball operations department," Ng said in the statement. 

"In our discussions, it became apparent that we were not completely aligned on what that should look like. I felt it best to step away."

Ng worked as Major League Baseball's vice president of baseball operations before joining the Marlins three years ago. She had also worked as an assistant general manager at the New York Yankees and Los Angeles Dodgers prior to that.

Her appointment by Miami was hailed as a landmark moment in the history of major professional sports leagues in North America. Ng was the first woman to be appointed general manager in any of the major leagues -- MLB, NBA, National Football League and National Hockey League.

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