File picture: ANA Pictures

Kinshasa - Unknown attackers killed a police officer during a raid on a jail in Democratic Republic of Congo's capital Kinshasa on Thursday, police and diplomatic sources told Reuters.

The raid took place just hours after the government said it had cancelled a major independence day military parade for security reasons.

It was not clear how the officer died, but gunfire was heard at the jail in the Matonge neighbourhood and dozens of heavily-armed police and soldiers were deployed to the area. Security was also reinforced around the state television building several kilometres away.

Sources were unable to say if any prisoners escaped. Government and local officials were not immediately available for comment.

"There was gunfire. I saw a woman wounded in her leg by a bullet," said one witness who asked not to be named.

Thousands of inmates have escaped from jails this year in Congo, including about 4,000 from the capital Kinshasa's main high-security prison last month, stoking fears that the security situation is deteriorating amid a growing political crisis.

President Joseph Kabila, in power since 2001, refused to step down at the end of his mandate in December, raising fears of a return to the civil wars of the turn of the century that killed millions.

Rising militia violence and a humanitarian crisis have unsettled Africa's largest copper producer in recent months.

Fighting between government forces and a local militia in the central Kasai region has killed more than 3,300 people and forced 1.3 million to flee their homes since August.

Congo will not hold its annual independence day military parade on Friday because of security concerns, an adviser to Kabila told Reuters on Thursday morning.

Independence day parades have been held in each of the last three years to mark the end of Belgian colonial rule in 1960 and have been used to show off the central African country's latest arms acquisitions.

Authorities ramped up security following the jail breaks, installing night-time checkpoints in Kinshasa's business district of Gombe.