NEW DELHI (Reuters) - A top Indian cotton-producing state has ordered an inspection of fields planted with an unapproved variety of genetically modified seeds developed by Monsanto, which is fighting to retain its market in the world’s biggest grower of the fiber.

Farmers in Andhra Pradesh have planted 15 percent of the cotton area in the state with Bollgard II Roundup Ready Flex (RRF), prompting the local government on Friday to form a panel of officials to “inspect the fields of farmers growing RRF”.

The order, issued by senior Andhra Pradesh official B. Rajasekhar, did not say how the farmers accessed the unapproved variety of genetically modified (GM) cotton. Calls to his office went unanswered.

“It’s a matter of grave concern that some seed companies, while suppressing their real intent of profiteering, are attempting to illegally incorporate unauthorized and unapproved herbicide-tolerant technologies into their seeds,” a Monsanto spokesman said.

“Commercial release of GM technologies in India without the requisite regulatory approvals may not only pose tremendous risks for the country’s farmers, it may also be in violation of applicable laws of the land.”

The spokesman did not identify the local companies.

Bollgard II RRF is a proprietary technology owned by Monsanto, the world’s biggest seed maker, which last year withdrew its application seeking approval from the regulator, Genetic Engineering Appraisal Committee (GEAC), for this variety.

The withdrawal was seen as a major escalation in a long-running dispute between the Indian government and Monsanto, which is also locked in a bitter battle with Andhra Pradesh-based Nuziveedu Seeds Ltd.

Monsanto applied for GEAC approval of Bollgard II RRF, known for its herbicide-tolerant properties, in 2007. When the U.S. company withdrew the application last year, it was in the final stages of a lengthy process that included years of field trials.

The illegal sale of the seeds violates India’s environmental protection rules, said C.D. Mayee, president of the South Asia Biotech Centre, a not-for-profit scientific society.

Mayee, a former government scientist, estimated that 3.5 million packets of such seeds were sold this season.

“Over the years, we have kept the regulators and key stakeholders apprised of the illegal usage of unapproved technology,” the Monsanto spokesman said.

“Even as late as August 2017, we have sought their intervention on the gross misuse of patented and regulated technologies which may pose numerous other challenges to India’s cotton ecosystem.”

A spokesman for the federal environment ministry was not immediately available for comment.

New Delhi approved the first GM cotton seed trait in 2003 and an upgraded variety in 2006, helping transform India into the world’s top producer and second-largest exporter of the fiber.