Lawyers representing three jailed Catalan separatists have lodged a case with the United Nations Working Group on Arbitrary Detention over their "unlawful" imprisonment.

Former regional Vice President Oriol Junqueras, and activists Jordi Sanchez and Jordi Cuixart face possible sedition charges. Junqueras is also investigated for alleged rebellion and embezzlement, punishable with decades in prison.

The three were jailed provisionally under a probe into events that led to an unsuccessful declaration of Catalan independence on Oct. 27 that violated Spanish law. Repeated applications for their release have been rejected.

British human rights lawyer Ben Emmerson said Thursday the detentions violate human rights and are aimed at repressing political dissent.

Spanish authorities have rejected similar claims and defended the judiciary's independence.