Draconian police powers which will allow officers to move on groups of two or more people near the site of the Olympic Games have come into force, prompting activists to patrol nearby streets in an effort to root out cases of "heavy-handed" policing.

Critics said the introduction of the Olympics Dispersal Zone bears resemblance to the Beijing Olympics, the organisers of which were criticised in the West over apparent attempts to stifle opposition.

"There is a direct comparison between the oppressive measures you see in other countries and this. You would not expect it in what is supposed to be a free, democratic country," said Claire Laker-Mansfield, who is organising a host of demonstrations in east London.

Her group, Youth Fight for Jobs, plans to defy the order by entering the dispersal zone en masse and refusing to leave if ordered to do so. She said the group is also planning static protests and marches in the coming weeks.

And members of the Newham Monitoring Project held two training days last month for volunteer legal observers, who will document cases where they believe powers are being abused during the Games.

The Newham Monitoring Project is part of a wider network of police watchdog organisations, which organisers said will "gather evidence of police misconduct and abuse of powers, both towards local people and during protests".