Montero told The Seattle Times he has never been a client of the clinic or even heard of owner Anthony Bosch until now, and that he has "no clue" why his name was in their records.
"I feel like I'm caught in the middle of something and I don't know why," Montero told the Times, noting that he's only been to Miami to visit family members and has never lived or trained there.
The Mariners issued this response Wednesday morning:
"The Seattle Mariners strongly support Major League Baseball's Joint Drug Prevention and Treatment Program, and are disappointed any time we hear of any players potentially involved with banned substances.
"We are aware of the report which appeared today in The New York Daily News and have been in contact with Major League Baseball to discuss it.
"This matter is now in the hands of the Commissioner's Office. At this time, with no additional information, we will have no further comment until that investigation has concluded, and all other questions should be directed to Major League Baseball."
The Miami New Times previously reported that Yankees third baseman Alex Rodriguez, Rangers outfielder Nelson Cruz, Nationals pitcher Gio Gonzalez and Minor Leaguer Cesar Carrillo were listed in the clinic's records, as were three players who have previously been suspended by Major League Baseball for using illegal synthetic testosterone or other banned substances: Blue Jays outfielder Melky Cabrera, A's pitcher Bartolo Colon and Padres catcher Yasmani Grandal.
Montero is a client of ACES, a Brooklyn-based sports agency operated by agents Sam and Seth Levinson. Cabrera, Gonzalez and Cruz also are represented by ACES, which has been under investigation by MLB since last August, when Cabrera was suspended for a positive test of elevated testosterone levels.
Seth Levinson issued a statement Wednesday afternoon denying any involvement with the Miami clinic.
"Anyone who knows us, knows that it is absolutely ridiculous to think that we would ever condone the use of performance-enhancing drugs," Levinson said. "Our work over the last 25 years demonstrates that ACES is built on a foundation of honesty, integrity and doing things the right way.
"Neither Sam nor I, or anyone else at ACES, have ever met or even heard of Anthony Bosch until the recent news stories, nor does anyone have any knowledge or connection to Biogenesis. Moreover, Juan Nunez ceased doing work on behalf of the agency as soon as his involvement in the Melky Cabrera matter came to light.
"The MLBPA's investigation into that matter found that we had no involvement in or knowledge of any wrongdoing. Similarly, in this case, we are not involved and do not have any knowledge as to what took place or who was allegedly involved."
In addition to Montero, Yahoo! Sports reported Tuesday night that three other players' names were found in the handwritten records of Bosch: Brewers outfielder Ryan Braun, Orioles third baseman Danny Valencia and Yankees catcher Francisco Cervelli.
Rodriguez and Gonzalez issued statements last week denying that they took performance-enhancing drugs, and Braun released a statement Tuesday night saying his name was found in Bosch's records because he and his lawyers used Bosch as a consultant during his successful appeal of a positive test last offseason. Braun's name was not listed next to any specific substances, and he said he never had a relationship with Bosch.
Montero, 23, is expected to be the Mariners' starting catcher this season after hitting .260 with 15 home runs and 62 RBIs last year while splitting time as a designated hitter and backup catcher. The club let veteran Miguel Olivo go after the season and traded John Jaso to the A's in a three-way deal that brought outfielder Michael Morse from the Nationals.
Montero is currently the only catcher on Seattle's 40-man roster, though veteran Ronny Paulino recently signed a Minor League contract with an invitation to Major League camp, and the club is believed to be close to signing Kelly Shoppach, who took a physical exam last week but has not yet been officially added. Top prospect Mike Zunino, the No. 3 overall selection in last June's First-Year Player Draft, is among three youngsters also invited to Major League camp.
Seattle's pitchers and catchers are due to report to Peoria, Ariz., on Tuesday. Montero is already at the team's facility working out in preparation for his second season with the club.