Three Catalan independence leaders have lodged a case with the UN Working Group on Arbitrary Detention, Reuters reports. The politicians have claimed that the custodial prison sentence they are serving in Madrid is unlawful, their lawyers said in London. Oriol Junqueras, Jordi Sanchez and Jordi Cuixart are accused of sedition for their roles in a secession drive in the northeastern Spanish region. The move involved an illegal referendum last October on a split from Spain and a subsequent declaration of independence, Reuters said.