Roger Lumbala was one of a few accused figures whose freedom or return from exile was agreed as part of the New Year's Eve deal.
Roger Lumbala, head of the small opposition Rally of Congolese Democrats and Nationalists (RCD-N), was one of a few accused figures whose freedom or return from exile was agreed as part of the New Year's Eve deal.
Lumbala, who allegedly backed the M23 rebellion in the country's east, arrived back in the DR Congo capital on board an Ethiopian Airlines flight, according to AFP journalists at the airport.
After mounting a failed presidential bid in 2006 elections, Lumbala had his lawmaker's mandate invalidated in January 2013 for repeated absence, as he was reported to have spent much time in Uganda and Rwanda.
Democratic Republic of Congo authorities accused him of "high treason" and complicity with M23 rebels, who were defeated in November 2013 after an offensive by government and UN forces.
As part of negotiations which led to the December 31 deal, a coalition centred on veteran opposition leader Etienne Tshisekedi demanded the release from prison or amnesty from prosecution for seven "symbolic" opposition figures.
All sides agreed to the "immediate" release from prison or return from exile of four of the seven, among them Lumbala, who thus became the first to benefit from legal action being abandoned.
On Friday, DR Congo's Roman Catholic church leaders, who mediated last month's deal, voiced concern at the "delay" in freeing political prisoners whose release had been agreed.
The New Year's Eve deal called for the appointments of a new prime minister and a transitional body to pave the way to elections in December 2017 that could bring an end to the rule of President Joseph Kabila.
The agreement was reached after months of violence and could set the stage for the first peaceful transfer of power in the DR Congo since its independence in 1960.