The Islamic Defenders' Front, a group known for sometimes violent campaigns against vice, had threatened to block Gaga's June 3 concert, saying she promoted Satan worship and homosexuality.

"We made the decision after considering objections from various Muslim groups who deem that Lady Gaga's stage act is not compatible with our culture," national police spokesman Boy Rafli Amar said.

More than 30000 tickets have been sold for the concert at the Bung Karno national stadium.

"If it's true that the concert has been cancelled. Indonesia is not a democracy, or a country based on the rule of law," said Semi Winarsih, a Gaga fan.

International acts are flocking to Indonesia, the world's largest Muslim-majority country, taking advantage of its strong economy and a growing middle-class with disposable income.

In the last year, pop stars such as Katy Perry, Justin Bieber and Kylie Minogue have performed in Indonesia.