SAG-AFTRA has filed an unfair labor practices charge alleging that advertising agency Grey Global produced non-union advertisements through 23 Townhouse.

Grey has denied the allegations, which were filed with the National Labor Relations Board. “We have said their contentions have no merit and we will respond accordingly,” spokesman Owen Daugherty said.

The performers union sent an alert on April 28 to its 160,000 members, saying that it had “serious concerns” about the issue. It said Monday that Grey has failed to cooperate with its investigation and that members had provided information about the non-union assertions.

“The member response to that alert has been overwhelming,” the union said. “We’ve received information about Grey Global, 23 Townhouse and other signatory ad agencies. Because the investigation is ongoing, we still need your help.”

Grey Global Group is a unit of communications conglomerate WPP Group. Subsidiaries include Grey, G2, GHG, GCI Group, MediaCom Worldwide, Alliance, G Whiz and Wing.

Grey is a signatory to the SAG-AFTRA commercials contract deal, which members ratified on May 9, so it’s not allowed to produce non-union ads. The successor deal contains a 7% hike in minimum wage rates and a 1.2% increase in employer contributions to health and retirements funds.

SAG-AFTRA launched a campaign last fall accusing ad agency Droga5 of using union performers for non-union work. Union reps left a petition with 8,000 signatures at the agency’s New York headquarters on Jan. 12. For its part, Droga5 insisted that it does not hire SAG-AFTRA members for non-union productions.

Here’s the entire message that was posted Monday on the SAG-AFTRA web site:

Please read this important notice regarding ad agency Grey Global and 23 Townhouse.

Because Grey Global Group failed to cooperate with our investigation of its possible production of non-union commercials through a front company, SAG-AFTRA filed charges today with the National Labor Relations Board. As a SAG-AFTRA member, we wanted you to know as soon as we took action. The NLRB will review these charges and determine if Grey Global is guilty as charged.

The possible connection between signatory ad agency Grey Global and 23 Townhouse (aka Townhouse 23) triggered our investigation of the potential use of 23 Townhouse as a front company for producing non-union commercials. The charges come after SAG-AFTRA formally requested information and documentation from Grey Global regarding its relationship to 23 Townhouse. We alerted you to this action on April 28.

The member response to that alert has been overwhelming. We’ve received information about Grey Global, 23 Townhouse and other signatory ad agencies. Because the investigation is ongoing, we still need your help. If you or anyone you know has worked on a 23 Townhouse production, tell us about it by clicking here.

Be on the lookout for any information about Grey Global and 23 Townhouse while on set. If you see anything of interest – including information about other signatory ad agencies producing non-union commercials – contact us at adsgounion@sagaftra.org.

A union staff member will follow up with you. Any info provided is confidential.