The Rwanda-backed M23 group has said it would not attend Tuesday's peace talks with the Democratic Republic of Congo (DRC) government in the Angolan capital, Luanda, following EU sanctions on some of its top brass.
But Kinshasa said on Monday it would participate despite the M23's announced no-show.
Tina Salama, the spokeswoman for DRC President Felix Tshisekedi, told the AFP news agency: "The Congolese delegation has left Kinshasa for Luanda. We will respond to the invitation for mediation" by Angola.
The M23, which has taken vast swathes of the DRC's mineral-rich east, on Monday accused "certain international institutions" of "deliberately sabotaging peace efforts", referring notably to sanctions imposed by the European Union.
"The successive sanctions imposed on our members, including those adopted on the eve of the discussions in Luanda, seriously compromise direct dialogue and prevent any advance," it said.
The group also denounced Kinshasa's "bellicose campaign" and added that "under these conditions, the holding of talks has become impossible. As a result, our organisation will not be able to take part in the discussions".
However, the Angolan presidency insisted late on Monday that the talks were on track.
"The delegation of the Democratic Republic of Congo for direct negotiations with M23 is already in Luanda," the presidency said on its Facebook page.
"The delegation of M23, in turn, will also arrive in the Angolan capital today. All conditions are created for the start of direct negotiations tomorrow, 18th March, as scheduled."
The European Union on Monday sanctioned three Rwandan military commanders and its mining agency chief over their support for armed fighters in the eastern Democratic Republic of Congo as well as senior members of the M23, including its head, Bertrand Bisimwa.
It also targeted the CEO of state-run Rwanda Mines, Petroleum and Gas Board "for exploiting the armed conflict" and a gold refinery based in Kigali.
TRT Global - The fallout comes as African leaders push for a ceasefire, with Rwanda accused of backing M23 rebels in DRC.
Prior no-shows
Since January, the M23 — which claims to defend the interests of Congolese Tutsis — has seized the key cities of Goma and Bukavu in a lightning advance that has killed more than 7,000 people, according to the DRC.
A report by United Nations experts has said Kigali effectively controls the M23 and has around 4,000 troops backing it in order to exploit the region's valuable minerals, such as gold and coltan.
Last year, the UN said M23 generated around $300,000 a month in revenue through its control of a mining area in eastern DRC.
Rwanda denies providing the M23 with military assistance but says it faces a threat in the DRC's east from the FDLR group, founded by ethnic Hutu leaders involved in the 1994 Rwandan genocide of the Tutsis.
The peace talks were scheduled to start on Tuesday in Luanda, as the African Union has appointed Angolan President Joao Lourenco to mediate in the conflict.
Tshisekedi and Rwandan President Paul Kagame were supposed to meet in Luanda in mid-December for direct talks, but they could not agree on the terms, and the summit was called off at the last minute.
The last time the DRC government and the M23 held talks was in 2013.
The armed group captured Goma in 2012 but was militarily defeated the following year by DRC armed forces supported by UN peacekeepers.
