* Provision alters court power during biotech lawsuits
* Farmers say they get the right to harvest a crop
* Biotech foes say backroom deal benefits seed companies
* Powerful Senate chair says she opposes the rider
WASHINGTON, April 3 (Reuters) - A number of U.S. farm groups want to extend a law that allows farmers to grow a genetically modified crop while regulatory approval of the variety is still being challenged in court.
No one in Congress claims ownership of Section 735 of a recent spending bill, but the 22-line provision has blown up a storm of opposition to what is being dubbed by critics as the "Monsanto Protection Act."
The legislation is lauded by some farm groups, who have vowed to try to extend the life of the statute beyond its Sept. 30 expiration at the end of the fiscal year.
Food safety advocacy groups frequently ask for a temporary injunction against sale of seeds when they challenge U.S. approval of genetically modified crops. So Section 735 would benefit biotech seed companies such as Monsanto Co and Dow Chemical Co.
"We'll certainly try to get that language put into the farm bill," Mississippi farmer Danny Murphy, president of the American Soybean Association, told Reuters.
He said lawsuits have delayed farmer access to profitable biotech varieties for years at a time. "We think it's important farmers have the certainty once they plant a crop they would be able to harvest it."
Lawmakers aim to pass a new farm policy law by this fall.
Only one variety, a genetically modified alfalfa developed by Monsanto, is under court review at present.
Biotech foe Andrew Kimbrell, executive director of the Center for Food Safety, called Section 735 a backroom deal that muzzles the power of federal judges to prevent the cultivation of inadequately reviewed biotech crops.
Opponents range from organic food advocates and small-farm activists to environmentalists, consumer groups and the American Civil Liberties Union.
The language was tucked into the 240-page government funding bill in the Senate with no indication of its author. Even the groups who support the provision say they do not know who got it into the sure-to-pass bill. No one claimed credit during debate.
The bill was passed on March 22 and signed by President Barack Obama on March 28 - even after thousands signed petition opposing the so-called biotech rider.
Monsanto, the world's largest seed company, is often a focal point for opposition by those who oppose genetically engineered crops or want more labeling of genetically modified foods. The company on Wednesday announced a 22-percent rise in quarterly earnings.
A pro-labeling/anti-Monsanto demonstration is planned for Monday at the U.S. Food and Drug Administration offices in College Park, Maryland.
Senior members of the Appropriations Committees in the House and Senate pointed at each other when asked who was behind Section 735. Two senators said the House panel was responsible because it backed the idea last year, albeit in a bill that failed to advance.
A spokesman for Representative Jack Kingston of Georgia, tabbed as the 2012 sponsor, said Kingston had no role this year.
Speculation has since centered on Senator Roy Blunt of Missouri, Monsanto's home state. His aides did not respond to queries.
Senate Appropriations Chairwoman Barbara Mikulski "didn't put the language in the bill and doesn't support it either," said spokeswoman Rachel MacKnight. She said Section 735 was an unavoidable carry-over from House-Senate negotiations last fall.
Mikulski has supported labeling of genetically modified foods and will fight for "valuable priorities, including food safety," said MacKnight.