Democratic Republic of Congo President Felix Tshisekedi called Thursday for young people to form "vigilance groups" in the face of M23 rebel activity in the east of the country.
Tshisekedi repeated in an address broadcast on national television that the M23 operated with "the support of Rwanda", which he accused of harbouring "expansionist ambitions".
A mostly Congolese Tutsi group, the M23 resumed fighting in late 2021 after lying dormant for years, accusing the Democratic Republic of Congo's government of failing to honour an agreement to integrate its fighters into the army.
The group's resurgence has destabilised regional relations in central Africa, with the DRC accusing its smaller neighbour Rwanda of backing the militia.
Tshisekedi said Rwanda had set its sights on "appropriating our minerals".
"To do this, it is working to destabilise eastern Congo to create a lawless zone to satisfy its criminal appetites," he said.
He added that diplomatic efforts to ease tensions have not led to "any tangible result".
The conflict, he said, would require "sacrifice", as well as "the engagement of all of (the nation's) daughters and all of its sons".
"In response to the strong demand from the youth, I invite them to organise themselves into vigilance groups with a view to propping up, accompanying and supporting our armed forces".
Tshisekedi also renewed his call for young people to enlist in the army, while cautioning against "stigmatisation of Rwandophone communities".
The M23 went back on the offensive in late October after several weeks of calm, grabbing multiple localities along an important road serving the strategic eastern city of Goma.
The DRC announced on Sunday that it was expelling Rwanda's ambassador, while also recalling its own envoy from Kigali earlier this week.