Troops from the 10-nation Southern African Development Community, SADC, have been discreetly arriving in DRC since the middle of December. They include soldiers from South Africa, Tanzania and Malawi.
"The SADC force has arrived," said lieutenant-general Fall Sikabwe, coordinator for military operations in North Kivu.
"These are professionals who are well equipped and well trained — units that can reverse the situation on the ground," he said.
The deployment of the regional force was decided at a SADC summit in May.
The troops will take over from an East African peacekeeping force, whose mandate was ended by Kinshasa which accused it of colluding with the rebels instead of fighting them.
Sikabwe said the new troops would engage in "an offensive mission to regain territory illegally occupied by the enemy," adding that those displaced could return home once this had been achieved.
After several years of dormancy, the M23 rebels took up arms again in late 2021 and seized vast swathes of the DRC's eastern North Kivu province.
Western governments and the United Nations have said neighboring Rwanda has supported the M23, allegations Kigali denies.
The DRC has asked for the withdrawal of the U.N. MONUSCO peacekeeping force which has started, the foreign minister said on Saturday.
It is due to be completed by the end of this year.
The U.N. Security Council voted in December to accept Kinshasa's demand for a gradual pullout of the MONUSCO mission, which arrived in 1999.
Despite a volatile domestic situation, the government had for months been calling for an accelerated withdrawal of the peacekeepers.
Kinshasa considers the U.N. force to be ineffective in protecting civilians from the armed groups and militias that have plagued the eastern DRC for three decades.
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