Down 2-1 in the best-of-seven American League Championship Series, the Houston Astros have been dealt another blow -- a complaint filed to Major League Baseball alleging a man associated with the Astros surreptitiously tried filming the Indians’ dugout during a playoff game last week.

MLB confirmed in a statement it was aware of a report by Metro Boston that a man claiming to be an Astros employee was removed from a credentialed area near the Boston Red Sox dugout during the ALCS opener at Fenway Park.

The Red Sox dropped that game but have taken the last two.

After the Indians lost the American League Division Series to the Astros in a three-game sweep last week, Cleveland said a man was seen with a cellphone standing by the photographers' pit at Progressive Field, the Indians' home park, on Oct. 8. The man was removed from the area “several times” by security personnel, a source told The Associated Press. The man's credential was requested by Houston, according to the source, who spoke on condition of anonymity because of the sensitivity of the matter.

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The league, in a statement obtained by an MLB reporter, said an investigation had been conducted and found that an Astros employee had been trying to make sure that the other team wasn't breaking any rules,

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"Before the Postseason began, a number of Clubs called the Commissioner's Office about sign stealing and the inappropriate use of video equipment. The concerns expressed related to a number of Clubs, not any one specific Club," the league said in a statement. They added that in response, MLB officials "reinforced the existing rules," in addition to putting in place "proactive measures," among which included "instituting a new prohibition on the use of certain in-stadium cameras."

"With respect to both incidents regarding a Houston Astros employee, security identified an issue, addressed it and turned the matter over to the Department of Investigations," the statement said. "A thorough investigation concluded that an Astros employee was monitoring the field to ensure that the opposing Club was not violating any rules. All Clubs remaining in the playoffs have been notified to refrain from these types of efforts and to direct complaints about any in-stadium rules violations to MLB staff for investigation and resolution. We consider the matter closed."

It was not immediately clear how or if the man in question is connected to the Astros, or if the Astros were doing anything illegal. But the two incidents have raised questions about the use of electronic equipment during games and whether the reigning World Series champions were gaining an unfair edge.

Last year, the Yankees and the Red Sox both accused each other of spying. After MLB found the Red Sox used electronic devices to steal hand signals from opposing catchers on the Yankees and other teams, the Red Sox filed a complaint alleging that the Yankees had used a camera from YES Network, co-owned by Yankee Global Enterprises, to relay signs during games.

Boston Red Sox center fielder Jackie Bradley Jr., left, and left fielder Andrew Benintendi. The Red Sox have taken the series lead against the Houston Astros. (AP)

According to the Metro report, which cited multiple security sources who were on the scene, the man in question was removed during the third inning of Game 1 on Saturday night at Fenway -- but allowed to stay in the ballpark after another Astros staffer intervened. The report said the man had a small camera and was texting frequently, but did not have a media credential.

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Red Sox manager Alex Cora said he heard about the report. Astros manager AJ Hinch said he was also aware of it.

"I'm aware of something going on, but I haven't been briefed," Hinch said. "I'm worried about the game."

When asked if he felt like anything was going on during the first two ALCS games at Fenway Park, Cora responded, "No, I don't."

This is not the first time this season the Astros have been accused of cheating.

Indians pitcher Trevor Bauer tweeted during the regular season that Houston’s pitchers may have been using banned substances to improve the spin on their pitches. Bauer didn’t provide any specifics or evidence to back up the claim, however.

Fox News' Elizabeth Zwirz and The Associated Press contributed to this report.