Police launched the raids early on Wednesday morning and searched over 20 buildings in the German capital.

No one has been arrested in connection with the raids, but police confiscated several items, such as computers and data carriers.

Police say they believe an organization with at least 15 members, and headed by an Islamist of Arab descent living in Berlin, has been planning terrorist attacks in Russia.

Several members of the group are also believed to have travelled to Pakistan to train in terror camps there.

The public prosecutor's office says the investigation is focusing on three men, aged 28, 30 and 36, but it did not provide any other details.

No imminent threat

Authorities would not comment on a report by the online version of German newspaper Bild that a group of Chechen Islamists were under investigation.

Germany has stepped up security measures in recent weeks in response to threats of attacks at Munich's Oktoberfest and on the day of the recent general election.

However, authorities said that Wednesday's raids were not connected to those cases.

"There is nothing that points to an attack in Germany," said a police spokeswoman.

Authorities said there was no information to suggest that attacks in Russia were imminent.

ca/dpa/AP/AFP

Editor: Nancy Isenson