British PM and celebrities in online plea for Suu Kyi

The "64 for Aung San Suu Kyi" campaign wants her 64th birthday on June 19 to be the last she spends under house arrest.

The campaign has been launched in Britain as Aung San Suu Kyi is on trial behind closed doors on charges of violating the conditions of her house arrest after a US man, John Yettaw, swam across a lake to her home.

It also comes as her supporters marked Wednesday the 19th anniversary of the election whose result was annulled by the military regime, leading eventually to her being placed under house arrest in 2003.

Brown's message, released by his office Wednesday, says: "I add my voice to the growing chorus of those demanding your release. For too long the world has failed to act in the face of this intolerable injustice. That is now changing.

"The clamour for your release is growing across Europe, Asia, and the entire world. We must do all we can to make this birthday the last you spend without your freedom."

The website also includes a letter signed by members of the "Not on Our Watch" campaign, including Clooney and U2 frontman Bono.