The Writers Guild of America East will strike against Neil Patrick Harris’ new variety show for NBC unless producer ITV Studios signs a WGA contract.

It was revealed Oct. 27 that the newly minted Oscar host had partnered with NBC to develop a variety show based on “Ant and Dec’s Saturday Night Takeway,” which airs on the U.K.’s ITV. NBC has ordered 10 episodes from ITV Studios America, all of which will be filmed in front of a live audience.

ITV America did not immediately respond to a request for comment. On Tuesday evening, Harris sent a Tweet asserting that the show will be produced under a WGA contract.

The WGA East, which has been in a protracted battle with ITV over unionizing the company, has warned that it will not allow its members to work on the show. In response to Harris’ tweet, WGA East exec director Lowell Peterson reiterated that the key issue is ITV’s willingness to sign a guild contract. It’s clear that the guild is leveraging the threat of disruption to the high-profile Harris project as a club against ITV, which has resisted the WGA East’s organizing efforts.

Peterson said in a statement that there is no doubt that “NBC would insist on (guild writers) – and of course so would Neil Patrick Harris. The problem is ITV. ITV needs to make a decision: to continue to fight the Guild and forego its role as producer, on the one hand, or to reach an agreement with us that honors its writers and writer-producers, on the other,” Peterson said.

In a letter sent Friday to ITV executives Ory Adelson and Adam Crozier, WGA East executive director Lowell Peterson said, “I am puzzled that ITV apparently intends to produce the show. I have tried to make the point with you and other ITV executives that fighting the guild is counterproductive for a company that seeks to solidify and expand its presence in American television.”

“We have already alerted our many hundreds of comedy-variety members to the fact that ITV is fighting the guild and will not agree to the standard terms of a collective bargaining agreement with us,” Peterson said. “Our members are puzzled that ITV expects to be able to employ them to write an important new NBC show while battling the guild at the bargaining table.”

The WGA has blasted ITV several times this year for alleged mistreatment of writers and producers on its shows.

“As bullish as companies like ITV are on the profit potential of reality television, the fact is that the men and women who actually make the shows toil under grueling conditions,” the guild said in a statement issued on Aug. 25, a few hours before Emmy Awards show began.

“Tight-fisted networks insist on impossibly tight production schedules,” the WGA East said at the time. “Writer-producers work up to 80 hours per week without time off – and without overtime pay. Injuries are rampant on field shoots. No one gets health or pension benefits.”

ITV responded on Aug. 25 by issuing a statement: “ITV Studios America is in ongoing talks with the WGA East and has no further comment at this stage.”

The WGA has organized three major reality-TV production companies – Sharp Entertainment, Optomen Productions, Lion TV – in recent years.

News about the WGA strike threat against the Harris-hosted show was first reported by Deadline.com.