The 39-year-old, identified only as Acuil A., was arrested on Saturday in Berlin, the federal prosecutor's office said in a statement.

A federal court judge then ordered him held in custody pending possible charges of working as a secret service agent.

Prosecutors alleged that, since at least July 2005, he had reported to the Sudanese intelligence service on the activities of Sudanese opposition supporters in Germany.

They did not say whether the man had responded to the accusations.