BANGKOK — Hollywood star Julia Roberts and detained Chinese activists are among celebrities and political prisoners tweeting and signing petitions for the release of Myanmar's democracy leader Aung San Suu Kyi as she approaches her 64th birthday -- her 14th spent in detention -- organizers said Sunday.

Suu Kyi will spend her 64th birthday Friday in Yangon's notorious Insein prison, facing charges of violating terms of her house arrest by harboring an American who swam uninvited to her lakeside home.

The ruling junta is widely expected to deliver a guilty verdict, which could put the Nobel Peace Prize laureate in prison for up to five years. She has already spent more than 13 of the last 19 years under house arrest.

"We must not stand by as she is silenced again. Now is the time for the international community to speak with one voice," Roberts wrote as part of a campaign -- "64 words for Aung San Suu Kyi" -- organized by a coalition of human rights and activist groups.

The campaign, launched May 27, asks Suu Kyi's supporters to tweet, write text messages or send video and photos to its Web site, http://64forsuu.org.

Similar campaigns on Suu Kyi's past birthdays and other milestones generated some global publicity for her cause but have failed to change the military junta's harsh attacks on all signs of dissent. Myanmar, also known as Burma, has been dominated by the military since 1962.

"Burma's generals think they can act with impunity. We'll have to wait until after the trial verdict to see if this time will be any different," said Mark Farmaner of Burma Campaign UK, one of the organizers.

Actress Demi Moore, actor Kevin Spacey, artist Yoko Ono and British Prime Minister Gordon Brown were among the contributors to the Web site. James Cameron, director of "Titanic" and "The Terminator," wrote, "While my heroes are fictional, Aung San Suu Kyi is a real-life hero and she needs help from you."

In a parallel campaign, the organizers have to date gathered the signatures of 107 former or current political prisoners from over 20 countries calling for the release of political prisoners in Myanmar and calling on the U.N. Security Council to impose a global arms embargo on the Southeast Asian nation.

"The continued denial of your freedom unacceptably attacks the human rights of all 2,156 political prisoners in Myanmar. As those also incarcerated for our political beliefs, we share the world's outrage," the 64-word message said.

The signatories include Kim Dae-jung, a former South Korean president and Nobel Peace Prize laureate; Shirin Ebadi, an Iranian human rights campaigner who also won the prize; former Czech President Vaclav Havel; and two female Chinese activists currently under house arrest, Yuan Weijing and Zeng Jinyan.

"Aung San Suu Kyi's continued detention shames Asia," wrote Kim.

Anwar Ibrahim, former deputy prime minister of Malaysia, urged the Association of Southeast Asian Nations to lift its policy of nonintervention in Myanmar, which is a member of the 10-nation bloc.

Organizers of the campaign include Human Rights Watch, the U.S. Campaign for Burma, Burma Info Japan, Open Society Institute, France's Info Birmanie and Amnesty International.