Mayor Martin J. Walsh brushed aside today a new court filing that shows he attended two meetings with a Boston Calling concert promoter that two of his aides are charged with trying to extort to hire union labor.

"That's not new information," Walsh told reporters. "One of the meetings is talking about having a beer pen, where alcohol was served. In the past there, you had to drink in kind of a segregated area, and we opened it up. And I think the second meeting was talking about how do we move forward, and they had a good, positive festival."

Walsh said he does not know the genesis of claims in court filings that one of his staffers told Boston Calling that union reps would inflate a giant rat outside the concert on City Hall Plaza if it didn't hire union workers, and said that would be a "problem" for the mayor.

"I don't know anything about that," Walsh said. "That was never brought to my attention, I know nothing about that. I don't know what they're talking about."

City councilor Tito Jackson, who will challenge Walsh in November, issued a statement calling on Walsh to "speak plainly and come clean rather than prolong this affair any further."

Walsh called the statement "political posturing."

"He was awful quiet on it before today," Walsh told reporters. "So maybe you should go back and ask him how come he wasn't so vocal about it, six months, a year ago."

As the Herald reported this morning, the new documents were filed last night in the criminal cases of two top-tier City Hall officials.

Private communications from the U.S. Attorney's Office to defense attorneys for Walsh's entertainment czar Kenneth Brissette and Timothy Sullivan, chief of staff for intergovernmental affairs, declare Walsh sat in on two meetings about the music festival in March and November 2014 during what prosecutors state was "the relevant time period" of their probe.

The missives were sent to the defense in response to their discovery demands and were made public by the defense as exhibits in a motion to dismiss charges of extortion and conspiracy against Brissette; and conspiracy against Sullivan.

Both men are on leave from their posts and both have both pleaded not guilty to the charges against them.

Prosecutors have accused Brissette and Sullivan of trying to strong-arm Boston Calling organizers to hire union labor.

Walsh, who is running for re-election, has fiercely attempted to distance himself from the scandal and has repeatedly said he has no fear of being indicted himself.

An Oct. 31 letter to defense attorneys Thomas Kiley and William Kettlewell, however, suggests his staffers were dropping his name to festival organizers to get what they wanted, even though organizers appealed to them that paying to take on members of the International Alliance of Theatrical Stage Employees would financially cripple them. The documents do not detail the nature of the meetings Walsh allegedly attended or what was discussed.

"The defendants stated that everyone had to get a fair shake and a shot at working this event," assistant U.S. Attorneys Laura Kaplan and Kristina Barclay told Kiley and Kettlewell. "They further stated that the mayor had a background in working with unions and wanted to find a way to bring everyone to the table to get everyone working together."

Christina Sterling, spokeswoman for the U.S. Attorney's Office, declined comment this morning, citing the pending case.

Prosecutors turned the Boston Calling meetings list over to the defense in response to a partially sealed hearing on Oct. 14 and subsequent order by U.S. District Court Magistrate Judge Judith G. Dein that they disclose to Brissette and Sullivan the "identification of the participants in the conversations during which the government contends the wrongful conduct took place; the dates and locations of the alleged conversations; and the substance of the alleged conversations."

Developing …