Congolese President Félix Tshisekedi has sent a government delegation to the Angolan capital of Luanda, while M23 also confirmed its participation.
In January, the Rwanda-backed group captured key areas of Congo’s mineral-rich east, escalating tensions.
This marks a shift from previous Angola-led peace talks, which excluded M23 and instead focused on Rwanda’s role in the conflict.
The abductions come as the Rwanda-backed group continues its rapid military expansion in eastern DR Congo, seizing key cities and escalating one of the most intense conflicts in over a decade.
Causing surprise across the bloc, Luxembourg has blocked the adoption of sanctions against Kigali. European ministers have suspended EU defence consultations with Rwanda.
The group, which has the backing of Rwanda, has recently captured the key cities of Goma and Bukavu in the east of the country.
EU foreign ministers agreed to impose political sanctions against Rwanda and M23 rebels in DR Congo, though Luxembourg opposes sanctions against Kigali until Friday.
Fighting with M23 rebels in eastern DR Congo has left at least 13 peacekeepers and foreign soldiers dead, UN and army officials said on Saturday.
M23 has made significant territorial gains in recent weeks, encircling Goma, which has around two million people and is a regional hub for security and humanitarian efforts.