BRUSSELS, July 7 (Reuters) - Belgium's Alcogroup and Sweden's Agroetanol were charged by EU antitrust regulators on Thursday with taking part in a bioethanol benchmarks cartel in previous years which could lead to fines.

The EU competition enforcer fined Spain's Abengoa 20 million euros last year for rigging ethanol benchmarks as part of a crackdown on such practices.

Abengoa admitted wrongdoing in return for a reduced fine but Alcogroup and Agroetanol disagreed with the European Commission which sent a charge sheet called a statement of objections to the companies on Thursday.

Agroetanol is made up of Lantmannen and its subsidiary Lantmannen Agroetanol AB.

"We are concerned that the companies' conduct harmed competition in the market for the supply of biofuels, which contribute to the reduction of greenhouse gas emissions. With artificially inflated biofuel prices, Green Deal objectives are also undermined," Commission Vice-President Margarethe Vestager said in a statement.

The Commission had previously said the cartel took place from September 2011 to May 2014.

Alcogroup and Agroetanol, which risk fines up to 10% of their global turnover if found guilty of wrongdoing, can submit their arguments in writing and also ask for a closed door hearing before the Commission makes a final decision. (Reporting by Foo Yun Chee; editing by Jason Neely)