MOSCOW (Reuters) - A Russian human rights Web site portal has been attacked by unknown assailants, forcing it to close down and move to a new address, the Web site said on Monday.

"This is a site to support the portal 'Human Rights in Russia' (hro.org) which has been attacked and has been temporarily withdrawn from service," the group wrote on its new Web site address hro1.org.

The group wrote that the Web site had stopped working properly on October 21 but that no person or group had claimed responsibility.

President Vladimir Putin is hugely popular in Russia but has been accused by the European Union and Russia's small and divided opposition of undermining democracy and gagging freedom of speech. He accuses Western governments of using human rights as a pretext to try to interfere in Russia's domestic affairs.

Russia holds a parliamentary election in December, and a presidential election in March to find a successor to Putin.