The protest Games: demonstrators target Olympics

Activists have promised they will defeat extra security to get their messages across

This summer's Olympic Games will take place against a backdrop of near-constant demonstrations, protesters have promised, as activists plan sit-ins, marches and occupations of key sites despite the huge security presence that will surround London 2012.

The vow came as the first major demonstration on an Olympic site – a protest camp against the construction of a training hall to be used during the Games – moved into its seventh day. Construction of the basketball facility at Leyton Marsh in east London was halted on Wednesday as protesters from Occupy London joined local residents who had set up camp there.

Olympic organisers were recently forced to more than double the number of security guards required for the Games from 10,000 to 23,700, pushing the cost of security up from £282m in 2010 to £553m in December 2011. They also announced earlier this month that 7,500 of the extra guards would be military personnel.

Police have also been given extra measures to deal with demonstrations, including the ability to fast-track the process of dismantling makeshift camps.

But a newly-established protest group Our Olympics, which acts as a forum for other activists to organise protests, said yesterday that it would get around the extra security, and promised the "greatest act of non violent civil disobedience of our time".

Games organisers Locog did not respond to a request for comment.