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On a cold winter night, more than 27 years ago, waves of a lethal gas escaped a chemical plant and swept over the ramshackle homes of this city's sleeping poor, killing thousands and sickening half a million people and making Bhopal synonymous with industrial disaster.

The survivors, still plagued by lingering illnesses, sick children, the holes left by dead relatives, faded away from the world's memory. Now, they have a serendipitous chance to seize perhaps the world's biggest stage to remind everyone of their existence — the London Olympics.

Bhopal activists, hoping to emulate the Tibetans who dominated headlines ahead of the 2008 Beijing Games, accuse Olympic sponsor Dow Chemical Co. of owing them compensation for their sorrow even though the giant corporation played no role in the accident. Dow disputes that it has any obligation, saying it purchased the company responsible for the Bhopal plant only after it had settled a liability case with India's government.

The suffering of the Bhopal victims, however, is undeniable.

Activists say that thousands of children born to parents directly exposed to the gas leak or poisoned by contaminated water are plagued by brain damage, cerebral palsy, stunted growth, cleft lips, missing palates. Cancer rates are inordinately high. Skin, vision and breathing disorders are endemic.

And for that prolonged suffering, the survivors have blamed both their own government and Dow. The government for negotiating a low compensation and then ignoring them. Dow, because 16 years after the tragedy it bought the Union Carbide Corporation, an American company that had a majority stake in the pesticide plant that leaked the lethal methyl isocyanate gas.

The rest of the Indian subsidiary was owned by Indian investors and financial institutions. Ten years after the tragedy, the subsidiary, Union Carbide India Ltd, was sold to an Indian company now called Eveready Industries.

But the anger of survivors, activists and now even the government has now primarily been focused on Dow, and the company's high-profile Olympic sponsorship has re-energized their desperate fight for justice.

They blocked trains by laying on rail tracks, wrote impassioned letters to officials and athletes, pushed the Indian Olympic Association and the sports ministry to lobby the International Olympic Committee to drop Dow as a sponsor. The sports ministry also hinted that a boycott could be an option.

Dow, which is sponsoring a $11 million decorative wrap that will sheathe London's Olympic Stadium, has long denied responsibility for the gas disaster. Dow says the legal case was resolved when Union Carbide settled with the Indian government for $470 million in 1989, a decade before it bought the company. It says all responsibility for the factory and any lingering contamination now rests with the state of Madhya Pradesh, of which Bhopal is the capital.

As the case has garnered renewed national attention and sympathy in India, the state's position has dramatically changed.

In 2009, Babulal Gaur, the state minister for Gas Relief and Rehabilitation told The Associated Press that the birth defects in the victims' children were mostly caused by poverty. He acknowledged the state owned the land where the now-shuttered plant stands.

However, on Tuesday he called Dow a "murderous" company and said the health woes of the survivors and their families were its responsibility.

Eveready, the Indian company that now owns the subsidiary that directly controlled the plant, has no responsibility, he said.

Survivors and the activists who support them argue that Dow's legal responsibilities are far from over. In recent years, the government has revived the case against Dow.

In February 2011, India's Supreme Court issued notices to Dow Chemicals and Union Carbide Corp. saying it will begin hearings on a government petition asking for an additional $1.7 billion in compensation for the victims.

Activists say its purchase of Union Carbide also makes Dow responsible for lingering contamination and other issues.

The IOC says Dow was not responsible for the gas leak and would continue as an Olympic sponsor. British Prime Minister David Cameron has backed that decision.

"Dow was not the owner of Union Carbide at the time, so this is a different company and a different business," Cameron has told the Indian broadcaster CNN-IBN.

Emails and telephones messages by The Associated Press seeking comment from Dow representatives in India and the US weren't answered.

The IOC's perceived insensitivity angers the Bhopal victims and those who have dedicated their lives to helping them, like Satinath Sarangi, director of the Sambhavna Trust Clinic, which offers free health care for those exposed to gas or polluted water.

"For Dow the Olympics are like the Ganga in which it will dip and wash away its crime," said Sarangi, referring to the ritual cleansing devout Hindus take in the sacred Ganges river.

But here, memories of running from the gas, watching bodies of friends, family and neighbors pile up on the narrow winding streets and in overwhelmed hospital wards can't be washed away.

"I can never forget that night as long as I live," says Balkrishan Namdev, a 55-year-old survivor and activist.

He remembers waking up feeling like he couldn't breathe. Like someone was burning chili peppers. Then there was just mad panic.

"Even the leaves of the trees turned black."

Those who suffered were already bitterly poor, most of them unskilled migrant laborers from rural areas. Most of the survivors of the gas leak lost the only skill they could barter for money — their ability to do hard labor.

Their poverty and political weakness left them vulnerable to the conditions that led to the world's worst industrial accident, and forced them to take compensation so low that it wouldn't even pay for a year's medicine for some survivors, Sarangi said.

Even today it's impossible to walk past a dozen homes in the slums that circle the compound of the old pesticide factory without finding a child with disabilities.

Dozens of parents bring their children for physical and speech therapy to a special school and clinic run by the Chingari Trust, a nonprofit organization run by two survivors.

Here, a 4-year-old girl is gently coaxed to put one skinny leg ahead of the other on a wooden beam on the floor. She can walk but has serious behavioral and sensory problems, her therapist says. Crowds send her into a panic. She suddenly falls down. She has problems sleeping and staying asleep.

Three-year-old Mohammed Imran Ali lies on a stretcher as his thin, twisted limbs are gently exercised. Other children with wasted limbs and vacant eyes smile and stare at visitors.

To spend even a few hours at Chingari, the word means "spark" in Hindi, is to know that long years after the fumes dissipated, the scars it left on Bhopal's minds and bodies are far from healed.

Targeting Dow's Olympic sponsorship, they feel, might be their last best hope to get justice.