Lawyers for security contractor DynCorp have accused a group of Ecuadorean farmers involved in a major legal battle against the company of repeatedly changing the facts of their claims. DynCorp asked the judge to dismiss several plaintiffs whose cases had been heading for trial in the U.S. District Court for the District of Columbia.

The new allegations were filed late Tuesday afternoon in a pair of lawsuits brought by farmers who say DynCorp aircraft sprayed their land with powerful, and possibly toxic, chemicals while on missions to eradicate Colombian coca farms. The spraying program is a part of Plan Colombia, a controversial U.S. effort to eradicate the country’s cocaine production. Some 2,021 farmers claim they suffered health problems and financial losses after their property was covered with the herbicides.