Franklin received a 10-day suspension by Major League Baseball on Tuesday for violation of the MLB's Joint Drug Prevention and Treatment Program.
"We are disappointed to learn this news but at the direction of Major League Baseball and following its rules, we are not able to comment further," a Mariners' club official said.
General manager Bill Bavasi, who is with the team in Detroit, told reporters, "It's a joint prevention program -- joint meaning that it's put together by the players and the owners who are very supportive of it." He did not comment further.
Franklin becomes the second player in the past two days to be suspended for failing a steroids test. Baltimore Orioles first baseman Rafael Palmeiro was suspended 10 days on Monday.
At a news conference held Tuesday afternoon at Comerica Park, where the Mariners opened a three-game series against the Tigers, the 32-year-old Franklin said he had no idea how he tested positive.
"There has to be a flaw in the system," he said. "I have no clue. I tested in [early] May and again three weeks later. The first was positive, the second was negative. There is a flaw in the testing or my urine got mixed up with somebody else's. They said that couldn't happen but I don't believe it.
"I just know deep in my heart that I'd never do anything like that."
The six-year MLB veteran said he was informed by phone of the positive test in May.
"I was like, 'Are you kidding me?' I had just woken up from a nap and thought, 'There's no way this is happening to me.' I thought it was a joke."
Franklin appealed the positive result and appeared before two arbitration committees. He said he was informed of the suspension on Sunday. Franklin, who helped Team USA capture the Gold Medal during the 2000 Summer Olympics in Sydney, Australia, has a 6-11 record and team-leading 4.61 ERA in 22 games, including 20 starts. He was scheduled to start Saturday night's game against the White Sox in Chicago.
He has a career record of 33-46 with a 4.19 ERA in six Major League seasons, all with Seattle.
"I'm one of the guys that was supportive of strong testing," Franklin said. "I believe I got to the big leagues on God-given talent, and that's how I've stayed here. It's hard to swallow. I know deep in my heart that I have never done anything like that."
Franklin said he has been drinking protein shakes and taking multiple vitamins purchased at a GNC nutrition store without incident. But he admitted that he never asked team trainers, or physicians, if it was OK.
He estimated that he has been tested six or seven times with only one positive result since he started taking the supplements in 2003.
He wouldn't discuss what he tested positive for, but did say that he stopped consuming all supplements after the positive test.
"I've spent a lot of nights thinking about it and I'll never take [supplements] again," he said. "I won't even take a vitamin until I'm done with baseball. I hate what's happened for the organization, me, and my family. I'm done with taking anything."
The Mariners must play their next nine games without Franklin, whose suspension ends on August 11, an off-day.
"I just have to take the 10-day suspension and get on with it," he said. "I've been thinking about it for two and a half months and I'm ready to get it over with."
Franklin said he would pitch simulated games and throw bullpen sessions to stay in shape.
"I know the Mariners' organization is standing behind me. People can think what they want to think, I guess."
Franklin becomes the eighth MLB player to be suspended under tougher drug rules enacted earlier this year. The others are Palmeiro, Mariners outfielder Jamal Strong, Indians pitcher Rafael Betancourt, Twins pitcher Juan Rincon, along with Jorge Piedra of the Rockies and outfielder Alex Sanchez, who currently plays for the Giants.
Jim Street is a reporter for MLB.com. Patrick J. Mooney contributed to this report. This story was not subject to the approval of Major League Baseball or its clubs.