An activist is planning the “greatest act of civil disobedience of our time” at this summer’s Olympics.

Occupy London protester Kerry-anne Mendoza, a 30-year-old University of London student, has set up an “umbrella” campaign group to bring together more than 30 organisations to cause chaos at the Games.

The groups are understood to be discussing potential targets, including the Zil traffic lanes for dignitaries and athletes to the Olympic Park, as well as attempting to disrupt security and the sporting events themselves.

Under the banner Reclaim London 2012, the group called OurOlympics, wants to use the Games as a “mouthpiece for the unheard majority”.

Its mission statement reads: “We believe that the London 2012 Olympics has been turned into a taxpayer-funded advertising campaign for some of the worst offending corporations in our world. We believe non-violent civil disobedience is the megaphone for the unheard majority. Let’s make sure they hear us at London 2012. We believe we can reclaim London 2012 by making it the greatest act of civil disobedience of our time.”

Occupy protesters today warned they are prepared to blockade building work at a multi-million-pound Olympic basketball practice hall in Leyton while local campaigners back their presence. About 20 have managed to halt work since the weekend. A group of residents furious at the development said Occupy will be welcome as long as the project threatens their green space.

Demonstrators at the Games will have to contend with a £553 million security operation — the largest mounted in peacetime in Britain — involving 12,000 police, 23,700 security personnel, 7,500 Ministry of Defence staff and 13,500 military personnel protecting the 34 venues and more than 60 non-competition Games venues from terrorist and civil threats.

MI5 is also mobilising 3,800 staff to focus on specific individuals who may pose a terrorist risk, its biggest operation since the war.

A spokesman for the Met said: “We have plans in place for a safe and secure Games and are ready to work with our partners on security matters including protests.”