Braun -- a five-time all-star and the National League's most valuable player in 2011 -- issued a statement Tuesday saying he had "nothing to hide" after published reports indicated his name was included in the records of Biogenesis of America, an anti-aging clinic founded by Anthony Bosch.
The New York Daily News reported Wednesday Montero's name also was listed at Biogenesis.
The Miami New Times reported last week the names of New York Yankees third baseman Alex Rodriguez and several other prominent players were found in a notebook of Bosch, who was previously linked to slugger Manny Ramirez, who was suspended by Major League Baseball for violating the league's drug policy in 2009.
Yahoo! Sports reported Tuesday Milwaukee Brewers outfielder Ryan Braun, the 2011 National League Most Valuable Player, had links with Biogenesis of America, which is the target of an MLB investigation.
Montero is a client of the New York sports agency ACES run by Seth and Sam Levinson, who represent Cabrera, who was given a 50-game suspension by MLB last summer after testing positive for elevated levels of testerone, and are being investigated by MLB as well.
New Times reported it obtained the records as part of its investigation into use of banned substances by professional athletes. The clinic closed last month and its records "are clear in describing the firm's real business -- selling performance-enhancing drugs, from human growth hormone to testosterone to anabolic steroids," the newspaper said.
Braun -- who tested positive for elevated testosterone levels during his MVP year and was suspended in 2012 -- said in his statement his relationship with Bosch was limited to consultation on issues involved in his appeal of the positive test result, including how samples can be tampered with.
Braun had the suspension overturned -- and retained the MVP award -- after arbitrators questioned the way in which his urine sample was handled.
"During the course of preparing for my successful appeal last year, my attorneys, who were previously familiar with Tony Bosch, used him as a consultant," Braun said.
"I have nothing to hide and have never had any other relationship with Bosch," he said. "I will fully cooperate with any inquiry into this matter."
New Times said names in Biogenesis' records also include pro tennis player Wayne Odesnik and Cuban star boxer Yuriorkis Gamboa.