LONDON — Benedict Cumberbatch, Keira Knightley, Jude Law and Steve Coogan are among 290 actors, directors, writers, musicians and other leading lights of the world of entertainment, the arts and culture calling for the U.K. to remain part of the European Union in an open letter published on British news sites Friday.

Britons vote in a June 23 referendum on whether to withdraw from the E.U., and the letter is the latest effort by those against a “Brexit” to sway public opinion. Polls show the vote too close to call.

Among the other actors signing the letter, derided as “luvvies” by the right-wing Daily Mail, are Helena Bonham Carter, “12 Years a Slave” star Chiwetel Ejiofor, Kristin Scott Thomas, Patrick Stewart and “The Wire” star Dominic West.

The letter states: “From the smallest gallery to the biggest blockbuster, many of us have worked on projects that would never have happened without vital E.U. funding or by collaborating across borders.

“Britain is not just stronger in Europe, it is more imaginative and more creative, and our global creative success would be severely weakened by walking away.”

Many in the entertainment industry have expressed concern over the impact a withdrawal from the E.U. could have on funding for British films and on competition for consumers on the continent.

Among directors backing continued E.U. membership are “Fifty Shades of Grey’s” Sam Taylor-Wood, Steve McQueen, winner of an Oscar for “12 Years a Slave,” “Slumdog Millionaire” Oscar-winner Danny Boyle, U.K. resident Alfonso Cuaron, an Oscar winner with “Gravity,” Stephen Daldry, Oscar nominated for “Billy Elliot,” “The Hours” and “The Reader,” and Stephen Frears, Oscar nominated for “The Grifters” and “The Queen.”

Top movie industry players who signed the letter include Andy Harries, Oscar-nominated producer of “The Queen,” “Harry Potter” producer David Heyman, “Carol” producers Elizabeth Karlsen and Stephen Woolley, Working Title chiefs Eric Fellner and Tim Bevan, Josh Berger, chair of the British Film Institute and a senior Warner Bros. exec in the U.K., and Pete Czernin, BAFTA-nominated producer of “The Best Exotic Marigold Hotel.”

The letter concludes: “From the Bard to Bowie, British creativity inspires and influences the rest of the world. We believe that being part of the E.U. bolsters Britain’s leading role on the world stage. Let’s not become an outsider shouting from the wings.”