WASHINGTON, (Reuters) – President Barack Obama has  put Ecuador on notice that it could lose valuable U.S. trade benefits unless the Andean country improves its treatment of foreign investors, U.S. business groups said yesterday.

Although Obama decided on Tuesday to extend Ecuador’s trade  benefits for six months, the concerns raised in a report he  sent to Congress suggests the preferences may not be extended  again, said Myron Brilliant, vice president for international  affairs at the U.S. Chamber of Commerce.

“We welcome the increased -scrutiny of Ecuador’s  eligibility going forward,” Brilliant said in a statement.

The Emergency Committee for American Trade, which lobbies  on behalf of U.S. multinational firms, said Obama’s report  reflected “the negative experiences of many U.S. companies that  have operated in Ecuador over time.”

Without mentioning any company by name, Obama noted  concerns about two outstanding investment disputes involving  U.S. companies in Ecuador.

One appeared to refer to a case brought by 30,000  Ecuadorean plaintiffs against Chevron Corp, which bought Texaco  in 2001.

The plaintiffs say Texaco polluted the jungle and damaged  their health by dumping billions of gallons of contaminated  water over more than two decades before leaving in the early  1990s. “The company argues that the Ecuadorian government bears  legal responsibility for any damage under the terms (of) a  release agreement,” Obama noted in his report.

“The government contests that argument. Concerns have been  raised that statements by top Ecuadorian officials in favor of  the plaintiffs have politicized the proceedings. The U.S.  government has encouraged Ecuadorian government officials to  refrain from commenting on ongoing judicial cases,” Obama  said.