SEAN PENN became the latest Hollywood luminary to join a growing American peace movement yesterday when he began a three-day visit to Baghdad. The move evoked memories of Jane Fonda’s trips to Hanoi during the Vietnam War, although “Baghdad Sean” does not have quite the same resonance as “Hanoi Jane”. The actor’s visit follows Tuesday’s open letter, signed by more than 100 American celebrities, urging President Bush to avoid a pre-emptive strike on Iraq, and signals a growing confidence among anti-war groups.

Also on Tuesday co-ordinated anti-war protests were held across America, in more than 150 towns and cities, organised by a coalition of 70 groups called United for Peace. More than 140 people were arrested in Austin, Chicago, New York, Sacramento and Washington, mostly for disturbing the peace.

This predictable involvement of America’s beautiful people against a strike on Iraq is attracting the most attention among newspapers and television networks, but the Beverly Hills activism receives a more mixed response from rank-and-file protesters.

While it highlights the cause, it can devalue the message. Last month Barbra Streisand sent a fax to Dick Gephardt, the outgoing House Minority Leader, quoting Shakespeare in her anti-war rhetoric. Not only did she misspell Mr Gephardt’s name, and call Saddam Hussein an “Iranian”, the Shakespeare she quoted was mistakenly gleaned from an internet parody of famous authors.

“Once again, Barbra Streisand has opened her alligator-sized mouth before her humming-bird brain has a chance to catch up,” the actor R. Lee Ermy said.

Penn, a Hollywood bad boy and former husband of Madonna, said: “As a father, an actor, a film-maker and a patriot, my visit to Iraq is for me a natural extension of my obligation to find my own voice on matters of conscience.” He added that the visit would enable him “to pursue a deeper understanding of this frightening conflict”. In October Penn paid for a $56,000 (£35,000) advertisement in The Washington Post, warning Mr Bush against a “pre-emptive attack on a separate sovereign nation”. He said: “I beg you, help save America before yours is a legacy of shame and horror.”

This week’s letter, which was sent to the White House, included signatures from the actors Kim Basinger, Mia Farrow, Martin Sheen and Olympia Dukakis. It followed an anti-war statement published in the Los Angeles Times and The New York Times signed by more than 4,000 people, including Sheen, Fonda, Susan Sarandon, Tim Robbins and Danny Glover.

This celebrity group is part of a larger collection brought under the umbrella of United for Peace, which is backed by religious and civic organisations, including the National Council of Churches, Business Leaders for Sensible Priorities, Veterans for Common Sense, the National Association for the Advancement of Coloured People and Physicians for Social Responsibility. Taken together, these groups represent a significant proportion of Americans. The leaders hope that the group will become an anti-war movement that will attract middle-class liberals.

“We will bring the anti-war movement to millions of people who have concerns and fears but have not had an outlet,” Michael Kieschnick, one of the organisers, said. “When those millions get engaged, whether through street events, letter writing, visiting the representatives . . . Bush will have to pause.”

The White House has responded: “Anti-war demonstrations are one of America’s time-honoured traditions.”

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