PHNOM PENH, Cambodia (AP) — Cambodia's Supreme Court has rejected an application for bail for an opposition leader charged with treason who is seeking to be released for medical treatment abroad.

The court ruled Friday that Kem Sokha must be kept in pretrial detention for his own safety and because the investigation into his case is ongoing. His Cambodia National Rescue Party was dissolved last November by a court ruling on a complaint by the government.

Kem Sokha's case is widely regarded as a political setup by the government to cripple its strongest opponent ahead of a general election this July. The party's dissolution was linked to Kem Sokha's alleged offense.

Kem Sokha's lawyers say he suffers from high blood pressure and diabetes, and has fallen sick in prison since being detained last September.