KINSHASA, Dec 6 (Reuters) - Vital Kamerhe, former chief of staff to Congolese President Felix Tshisekedi, has been granted provisional release from prison where he was serving a 13-year sentence for embezzling $48 million in public funds, his lawyer said on Monday. Kamerhe started his sentence last year after becoming the most senior politician to face trial for graft in Democratic Republic of Congo, where high-level corruption is endemic. A high court has now granted him provisional release, lawyer Kabengela Ilunga told Reuters. He did not say why Kamerhe was being released or on what terms. There was no immediate comment from the authorities, but a presidential source confirmed the court"s decision. At the time of his trial, Kamerhe denied stealing money earmarked for social housing under Tshisekedi"s flagship 100-day building programme. The veteran power broker backed President Felix Tshisekedi in his successful 2018 election campaign in return for Tshisekedi"s support the next time around in 2023.