The Philippine government filed a criminal case in court on Wednesday against a staunch critic of President Rodrigo Duterte, accusing her of trying to sabotage a congressional investigation into her alleged involvement in the drug trade.

The justice ministry's case against Sen. Leila de Lima, its former head, says she deliberately skipped the inquiry by the House of Representatives and told her ex-driver and alleged bagman to go into hiding and ignore a legislative summons.

De Lima is among only a few high-profile domestic critics of Duterte's campaign against drugs, which has killed about 6,000 people, roughly a third in police operations. The other deaths are classified as under investigation, with many believed to be the work of vigilantes.