Robert Mintz has resigned from the board of directors of downtown Los Angeles apparel maker American Apparel Inc., according to documents filed Wednesday with the Securities and Exchange Commission.

Mintz, a director at former American Apparel lender Lion Capital of London, will be replaced by Jeff Chang, another Lion director. Lion holds one American Apparel board seat and has the power to appoint more board members.

Mintz resigned from the board on March 5. Lion had named him to American Apparel’s board under a 2009 investment agreement with the company.

A source close to American Apparel said Mintz left the board because he was frustrated with its current investors, New York investment firm Standard General, which controls five board seats out of nine.

Another source close to the company attributes Mintz’s departure to a dispute over private expenses not being reimbursed.

Mintz was unable to comment in time for publication.