BOSTON —Another top official at Boston City Hall has been arrested for pressuring music festival organizers to hire union workers.

Timothy Sullivan, the acting director of intergovernmental affairs, was arrested Wednesday, following a federal grand jury indictment, U.S. Attorney Carmen Ortiz’s office announced.

The 36-year-old Boston resident faces conspiracy to extort a company and extortion charges. He was arraigned Wednesday in Boston federal court.

Mayor Marty Walsh, a former labor union leader, said he’s “deeply concerned” about the allegations. He told reporters at an unrelated appearance Wednesday that Sullivan and Kenneth Brissette have been placed on paid administrative leave, pending the criminal cases.

“There is no room in my Administration for the type of behavior that is alleged here,” Walsh said in a statement. “It is a great privilege to serve in City Hall and I will not allow anyone to squander that privilege.”

Sullivan’s arrest comes after Brissette, director of the city’s Office of Tourism, Sports, and Entertainment, was arrested and charged with extorting the same company in May.

Brissette, 52, has pleaded not guilty.

The two men are accused of pressuring the Boston Calling music festival’s production company into hiring workers with Local 11 of the International Alliance of Theatrical Stage Employees by withholding required city permits and approvals in 2014.

The multiday rock and pop music festival has taken place on City Hall Plaza in downtown Boston twice a year since it debuted in 2013.