He is DR Congo's first freely elected leader in 40 years having defeated Jean-Pierre Bemba in a tense run-off presidential election in October.

The 35-year-old took power in 2001 after his father was assassinated.

He headed a transitional government during the past three years after a peace deal to end a five-year war.

Thousands of guests were in the garden of State House just near the huge and powerful Congo river.

Many people were shading themselves under umbrellas in the national colours of blue, red and yellow.

Several African leaders attended the event including South Africa's President Thabo Mbeki and the Angolan leader, Jose Eduardo dos Santos.

But Bemba did not attend the swearing-in ceremony yesterday. President Robert Mugabe of Zimbabwe is also not attending - despite being a close ally of Joseph Kabila's father, Laurent.

Last month, the Supreme Court rejected a legal challenge by Bemba, who claimed the run-off vote was rigged.