The clashes come after President Joseph Kabila was named winner of a November 28 election that was rejected by the opposition over allegations of fraud, and criticized by international observers for procedural chaos and irregularities.

Kabila was sworn in for a new term in the vast central African state on December 20.

Riot trucks and pickups loaded with police carrying teargas grenade launchers and rifles zoomed through Kinshasa's streets, while tanks and heavy armed republican guard sporting red berets were deployed inside the stadium grounds where Tshisekedi had planned his rival swearing-in ceremony.

The poll was the second since a 1998-2003 war that killed more than 5 million people, and was meant to shore up the country's fragile gains at stability.