The US' Screen Actors Guild has come out in support of the threatened actors' strike by UK performer's union Equity, instructing its members to seek SAG advice before accepting work on any UK production.

The SAG support is a boost to Equity's ongoing dispute with UK producers, which centres around attempts to secure payments for UK actors from ancillary revenue streams. SAG said it will instruct its members "whether acceptance of any specific offer will adversely affect Equity's effort to obtain a fair contract."

The proposed Equity strike is to take place from December 1, and threatens to severely disrupt UK production. Last week, however, the union issued guidelines to producers who wanted to side-step the strike by calling for them to provide actors paid a slice of revenues.

Warner Bros, for example, has struck a deal with Equity on residual payments for actors to allow the second installment of Harry Potter to be filmed in the UK. Many independent productions looking to shoot in coming months are also striking deals with Equity to give actors additional payments.

Amongst the first is IAC Film's Cromwell And Fairfax, which is to star Tim Roth and Dougray Scott. "It's the only way to be safe," said IAC's Guy Collins.

In a statement, SAG said its board had "voted unanimously to support its fellow union members of British Equity in their contractual negotiations for a new theatrical motion pictures contract."