PHILADELPHIA (AP) — A top official at an ironworkers' union was sentenced on Thursday to eight years in prison in what federal prosecutors say was a campaign of violence and intimidation to coerce building contractors into hiring his workers over non-union competition.

Edward Sweeney, a former business agent of Ironworkers Local 401, received the sentence after he admitted a role in two arsons, one arson attempt and 10 extortion attempts, prosecutors said.

Arson targets included a Quaker meetinghouse in the tony Chestnut Hill section of Philadelphia and a Toys R Us store in suburban Philadelphia.

Sweeney, 56, pleaded guilty in September to racketeering and arson charges. Prosecutors said he threatened contractors, organized picket lines and arranged arsons, property destruction and other efforts to sabotage construction sites.

Sweeney was one of the most vocal supporters of using violence, arson and other criminal sabotage against non-union contractors or even other unions he believed to be performing ironworking tasks, prosecutors said. He provided an acetylene torch to Ironworkers who carried out acts of sabotage, and he slashed the tires of a non-union contractor's vehicle, prosecutors said.

He even told a non-union contractor that "all you got to do is hire a couple of guys" and the acts of sabotage against the construction site would end, prosecutors said.

In a grand jury indictment unsealed last year, prosecutors said the Ironworkers created goon squads to carry out the assaults and property destruction against non-union contractors. One goon squad referred to itself as T.H.U.Gs, short for The Helpful Union Guys.

Sweeney testified in January against the longtime union head, Joseph Dougherty, who was convicted. A defense lawyer said Dougherty never directed his members to commit crimes and should not be held responsible for them.

All told, 12 men were charged and 11 pleaded guilty. Nine have been sentenced.