Police searched apartments and offices run by leftist groups in cities across the country Wednesday on suspicion they were planning "terrorist" attacks against next month's Group of Eight summit.

"The militant extreme left groups and their members are suspected of having founded a terrorist group, or of being members of such an organization, with the specific goal of staging fire bombings and other violent attacks in order to disrupt or prevent the upcoming G-8 summit in Heiligendamm," federal prosecutors said in a statement.

Prosecutors said they were investigating more than 18 individuals suspected of organizing a terrorist group.

More than 900 federal and local police officers in cities including Berlin, Hamburg and Bremen searched some 40 premises used by various leftist groups, the statement said.

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The Berlin-based Antifa group said the searches were directed against activists who were involved in organizing protests against the summit.

The prosecutors were "looking for electronic data and proof for the funding of a militant campaign against the G-8 summit," Antifa said.

Prosecutors said they had focused on dismantling a particular server where they said many leftist groups and projects maintained their Web sites and mailing lists.

"The only point of these searches is to criminalize and disrupt the protests against the G-8," the Anti-Fascist Leftists of Berlin said in a statement. "The accusation that terrorists would coordinate their movements through a leftist-run Internet server is ridiculous."

Germany's federal investigators have expressed concern about possible attacks during the G-8 summit over the past several months.

In December, anti-G-8 activists had splashed paint on a hotel in Heiligendamm, the Baltic Sea resort in northeastern Germany where world leaders are to meet next month.

Security officials in Hamburg also cited a number of other lower-scale attacks, including several firebombings there.

In the past, G-8 summits have been overshadowed by violent protests. In Genoa in 2001, protesters and police battled in the streets for days.

German security officials have built a $17-million fence around Heiligendamm, hoping to keep protesters away from the summit.

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