A statement from the union reads: 'Guild members are reminded of their obligation not to accept employment on any non-signatory project, as well as their obligation to confirm with the guild that a project is signatory. Employment on any non-signatory project within the guild's jurisdiction may subject a member to a Rule One violation.'

The union did not have jurisdiction over rehearsals and behind-the-scenes footage during filming, which it expects to be a feature release.

Jackson was set to take the stage in July, just weeks before he died from a suspected cardiac arrest June 25.