A coalition of more than 2,000 U.S. farmers and food companies said Wednesday it is taking legal action to force government regulators to analyze potential problems with proposed biotech crops and the weed-killing chemicals to be sprayed over them.

Scientists, environmentalists and farm advocates are pressing the question about whether rewards of the trend toward using more and more crop chemicals are worth the risks, as the agricultural industry strives to ramp up production to feed the world's growing population.

The debate has heated up in the last several weeks, with a series of warnings and calls for government action including a lawsuit against the U.S. Environmental Protection Agency.

Monsanto Co said on Friday that it had settled a long-running legal battle with residents of West Virginia who claimed they suffered environmental and health problems tied to pollution from a former Monsanto chemical plant.

St. Louis-based Monsanto, which has shifted from a concentration in the chemical business to agricultural seeds, said it would commit to more than $90 million in clean-up, remediation and medical monitoring to resolve a series of class action lawsuits involving a plant once located in Nitro, West Virginia.

The United States remained the primary backer of biotech crop technology in 2011, but adoption spread internationally as the total global planted area of genetically modified seeds grew 8 percent from a year ago, according to a report issued Tuesday.

Roughly 160 million hectares, or 395.2 million acres, were planted with biotech crops in 2011, up 8 percent from 2010, said the International Service for the Acquisition of Agri-Biotech Applications (ISAAA) in its annual report on biotech seed use.

Opponents of Monsanto's new genetically modified sweet corn are petitioning national food retailers and processors to ban the biotech corn, which is not labeled as being genetically altered from conventional corn.

A coalition of health, food safety and environmental organizations said they have collected more than 264,000 petition signatures from consumers who do not want to buy the corn.

Record-breaking triple-digit temperatures were prolonging a devastating drought that has been baking the South and the dry spell could extend into next year and beyond, climate experts said on Thursday.

"Just when you thought it couldn't get any worse... we are seeing expansion of this drought. This drought will continue to persist and likely intensify," said climatologist Mark Svoboda, with the University of Nebraska's National Drought Mitigation Center.

Significant levels of the world's most-used herbicide have been detected in air and water samples from two U.S. farm states, government scientists said on Wednesday, in groundbreaking research on the active ingredient in Monsanto Co's Roundup.

"It is out there in significant levels. It is out there consistently," said Paul Capel, environmental chemist and head of the agricultural chemicals team at the U.S. Geological Survey Office, part of the U.S. Department of Interior.

U.S. ethanol production bounced back in the last week with good demand helping offset high prices for key ingredient corn.

The Energy Information Administration said on Wednesday that U.S. ethanol production totaled 904,000 barrels per day, up 5,000 barrels per day from the previous week.

"Production is up because demand remains strong and margins are as well," said analyst Tom Waterman. "Ethanol prices continue to accelerate when corn moves up."

Ethanol stocks rose to 18.24 million barrels, up 661,000 barrels over the last week, the EIA said in its weekly report.

A band of showers has offered some relief to parched areas from Kansas to Mississippi, but the historic drought causing billions of dollars in losses in the South is showing no signs of abating soon.

Some parts of hard-hit Texas saw more rainfall in one day last week than they have seen all year. Still, much more would be needed to help that state, which has more than 90 percent of its land area suffering "extreme or exceptional" - the worst levels of drought.

A devastating drought deepened over the last week in many areas, spreading through more of the Plains and going into the Midwest as triple-digit temperatures baked already thirsty crops and livestock.

The Corn Belt states of South Dakota, Iowa, Illinois and Indiana saw drought develop quickly as the important corn-growing region got only spotty rainfall amid the high heat, according to the weekly U.S. Drought Monitor, produced by a consortium of national climate experts.

Abnormal dryness intensified to moderate drought over the last week, according to the report.