ARLINGTON, Texas -- Major League Baseball commissioner Rob Manfred said he believes the sign-stealing scandal that has engulfed the sport involves only the Houston Astros and that he can mete out discipline beyond the standard fine and draft pick penalties if necessary.

Speaking as the owners meetings began Tuesday, Manfred called the allegations of technology-driven sign-stealing by the Astros "the most serious matter." He said "it relates to the integrity of the sport" and promised "a really, really thorough investigation."

"Right now, we are focused on the information that we have with respect to the Astros," Manfred said after a tour of Globe Life Field, the Texas Rangers' new stadium set to open in 2020. "I'm not going to speculate on whether other people are going to be involved. We'll deal with that if it happens, but I'm not going to speculate about that. I have no reason to believe it extends beyond the Astros at this point in time."

Cheating accusations are commonly levied by teams against other teams in discussions with officials in the commissioner's office, although none had taken hold until former Astros pitcher Mike Fiers alleged the 2017 World Series champions used a camera feed near the home dugout to steal catchers' signs and relayed them to hitters by banging on a trash can.

Fiers' allegations prompted the league to open an investigation, which thus far has focused on the 2017 Astros but has included questions about more recent Astros teams, sources told ESPN.

The maximum penalties Manfred has handed out include a $2 million fine and docking of two first-round draft picks after a St. Louis Cardinals employee illicitly accessed the Astros' proprietary database, and a ban on international signings after an investigation into the Atlanta Braves' practices in Latin America.

MLB instituted new rules before the 2019 season in hopes of limiting stealing signs via technology, and the scope of Manfred's discipline could depend on the timing of any alleged wrongdoing.

"I'm not going to speculate on what the appropriate discipline is," Manfred said. "That depends on how the facts are established at the end of the investigation. The general warning I issued to the clubs, I stand by. It certainly could be all of those [past disciplinary actions], but my authority under the major league constitution would be broader than those things as well."

Manfred said he does not have a timeline for the investigation, but "I certainly would hope that we would be done before we start playing baseball again."

Discussion of the Astros, sources told ESPN, is expected to be a common topic at the owners meetings, which run through Thursday.

The fear among a number of top executives, sources said, is that the practice of technology-driven sign-stealing has become commonplace in the game and that the Astros' case will serve as a litmus test for Manfred's ability to clamp down.

"Any allegations that relate to a rule violation that could affect the outcome of a game or games is the most serious matter," Manfred said. "It relates to the integrity of the sport. In terms of where we are, we have a very active -- what is going to be a really, really thorough investigation ongoing. But beyond that, I can't tell you how close we are to done."