Protest organizers Bellona, a Norwegian environmental group, said the activists had been roughed up by Russian police at the rally, which was held to demonstrate against the storage of nuclear waste in Russia.

"Thirteen environmentalists including the deputy head of Ecodefense (a Russian group), Vladimir Slivyak, and a Bellona member, Vera Ponomaryova, were beaten and arrested by police in central Saint Petersburg," it said in a statement.

Local police confirmed the arrest to AFP but declined to comment on the reported rough treatment of the group. They did not say whether the 13 were still in custody late Tuesday.

The unauthorized protest was broken up only minutes after it started.

Russia stores considerable amounts of nuclear waste. On Tuesday it denied that it would use the Group of Eight nations summit this weekend to negotiate taking in nuclear waste from the United States.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.