Congo's leader has called on young people to enlist in the army to help fight Rwanda-backed rebels attempting to seize more territory in the country's conflict-battered east.

Rwandan President Paul Kagame blasted criticism of his country's role in eastern Democratic Republic of Congo where rebels his government backs have seized its largest city, saying Kigali is prepared for "confrontation" if necessary.

Much of the beleagured city of Goma was calm early Wednesday morning, after a day during which thousands of fleeing people hunkered down by roadsides as missiles flew and injured people streamed to overwhelmed hospitals.