Green groups have formed a coalition against three high-profile London 2012 sponsors, the latest in a wave of protests that have heightened fears that demonstrators are ramping up their campaigns in the run-up to the Games in nearly 100 days' time.
The coalition, which launched the campaign 'Greenwash Gold 2102' today, argues that Dow Chemical, oil company BP and mining giant Rio Tinto should not be involved in the Olympics because of their environmental records.
The campaign, which includes activist groups the Bhopal Medical Appeal and UK Tar Sands Network, is one of a collection of protests ranging from local communities fighting construction of venues in their neighbourhood to trade unions complaining about work conditions.
Protests have been peaceful, but police and Olympic chiefs are aware the Games, and torch relay, could be a magnet for demonstrators keen to publicise their message at a time when the world's attention will be on London.
Security threat from 'lone wolves'
Britain will mount its biggest peacetime security operation for the Olympics, with "lone wolf" attacks causing most concern but a range of other threats also under surveillance.
A security force of more than 40,000, backed by a huge intelligence operation, will guard venues, athletes and the millions of visitors expected to throng the British capital.
The halting of the Oxford and Cambridge University Boat Race by a protester swimming in the River Thames this month highlighted the difficulty of ruling out a disturbance at the Games. Cyber-attacks, crowd trouble, riots, civil emergencies and even extreme weather are among the scenarios that British authorities are planning for, officials and analysts say.