SAO PAULO, July 15 (Reuters) – Creditors in bankrupt miner Samarco Mineracao SA, a joint venture between Vale SA and BHP Group PLC, made on Thursday an objection to the company's restructuring plan, according to a court document.

Creditors said the plan's main goal is to protect Samarco's giant shareholders, Vale and BHP, and reduce future payments to creditors.

They also rejected Samarco's offer to apply an 85% haircut to all creditors, including shareholders Vale and BHP, which extended 24 billion reais in loans to the company. Payments would occur in 2041.

Creditors said both Vale and BHP, as shareholders, should be paid only after all other creditors fully recover their money. They also questioned if both giant companies should recover any value as creditors consider that both miners are co-debtors.

They also refused Samarco's offer to swap their debt into shares in the company.

"It is unacceptable that a restructuring plan of a company controlled by the world's biggest miners outline a outright (and illegal) debt forgiveness to create value for its multimillionaire shareholders, which are also responsible for Brazil's biggest environmental disaster," creditors said in the court document.

The collapse of a dam at the Samarco mine complex in 2015 killed 19 people, severely polluted the Doce River with mining waste and led the company to financial trouble.

Creditors have proposed Samarco, Vale and BHP pay in three equal parts for all damages caused by the rupture of the dam, creditors lawyers Paulo Padis and Marcos Pitanga said in an interview. That contrasts with Samarco's restructuring plan, which proposes the company pay for damages entirely.

(Reporting by Carolina Mandl; Editing by Sam Holmes)