Human rights and environmental pressure groups have joined forces today in a campaign against three sponsors of the London Olympics.
The protest campaign - called Greenwash Gold 2012 - have Dow Chemical Company, BP and Rio Tinto in their sights.
Meredith Alexander, who quit as a commissioner of the 2012's sustainability watchdog in protest over the link between the Bhopal disaster and Dow Chemical Company's involvement with London's showpiece Olympic Stadium, is chairing the campaign launch.
The group has made three short animated films about the companies and members of the public will be invited to vote online for the "worst corporate sponsor of the Olympics".
Ms Alexander said: "The Olympics are meant to be about so much more than how fast Usain Bolt can run or how many medals Britain's finest athletes score.
"The modern Olympics was founded here in the UK to promote peace and understanding between the peoples of the world.
"The Olympic values are all about celebrating our common humanity.
"But the Olympics is also big business. There is an expensive machine behind the Games that is funded by corporate sponsors. Sadly when these sponsors are selected, money talks much more loudly than values.
"As an ex-member of the Commission for a Sustainable London 2012, I know first hand just how little scrutiny is allowed when sponsors are chosen. Greenwash Gold 2012 is a chance to turn this around by letting the public vote for the least ethical sponsor."
All three companies have defended their ethical record.
Up to 15,000 people died and tens of thousands were maimed when poisonous gas leaked from the Union Carbide factory in Bhopal in central India in 1984. It is one of the world's worst industrial disasters.
Dow bought Union Carbide in 2001 and denies responsibility for Carbide's Bhopal liabilities.
Dow, a global Olympic sponsor since 2010, has stepped in to fund the high-tech fabric wrap for the 2012 Olympic Stadium which was ditched to save £7 million. Savings of £20 million had been called for.
Dow has always maintained it did not own or operate the Bhopal plant and that legal claims regarding the gas leak were resolved when Union Carbide paid £303 million in compensation for those killed or injured. The Indian government is seeking an additional £1.1 billion for the victims.