A car bomb has exploded outside a police station in the Colombian city of Cali, killing at least five people.

Four of the dead are police officers; the fifth is said to be the driver. No-one has admitted responsibility.

The attack comes three days before President Alvaro Uribe - known for his hard line against left-wing rebels - is due to be sworn in for a second term.

Colombia has seen decades of fighting among rebels, right-wing paramilitaries and state forces.

Friday's bomb reportedly exploded as the car passed in front of a police station in the El Vallado neighbourhood in the east of the city - Colombia's second largest.

The blast produced a column of smoke which rose above Cali, the Associated Press news agency reported.

Several people injured in the blast - including four police officers - were taken to hospital, Efe news agency reported.

El Valle state Governor Angelino Garzon told a local radio station he blamed leftist rebel group the Revolutionary Armed Forces of Colombia (Farc) for the "terrorist" attack.