UPDATESAG-AFTRA is investigating advertising agency Grey Global for allegedly producing non-union advertisements through 23 Townhouse — an allegation that Grey has denied.

The performers union sent an alert Thursday to its 160,000 members, saying that it has “serious concerns” about the issue.

“The union believes Grey Global may be trying to produce non-union commercials through 23 Townhouse and avoiding its commitment to the wages, terms and conditions in the SAG-AFTRA Commercials Contracts,” it said. “We have tried to contact Grey Global about these potential violations — without success. Today, in the absence of a response from Grey Global, the union issued a formal Claim and Information Request in advance of potential arbitration and NLRB actions.”

Grey Global spokesman Owen J. Dougherty said in response, “Grey is a long-standing signatory of SAG.  We have had a very positive and productive relationship with them.  We believe that there is no merit to their contentions. Contrary to their open letter, no one from SAG tried to contact Grey Group before it was released.  We intend to respond to their letter in due course.”

The union also said that members should contact a rep if they have any knowledge about anyone who has worked on a 23 Townhouse production.

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.

SAG-AFTRA reached a tentative deal on April 3 with the ad industry on a commercials contract, which contains a 7% hike in minimum wage rates and a 1.2% increase in employer contributions to health and retirements funds. The union has sent out the three-year proposed deal to its 160,000 eligible members for ratification.

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.