KINSHASA (Reuters) - Congolese security forces killed at least 14 members of separatist sect Bundu dia Kongo (BDK) on Monday during clashes in the capital Kinshasa and southwestern city of Matadi.

At least one police officer also died, police said.

The clashes followed an attack by BDK members on Kinshasa’s main prison and demonstrations by other members against Democratic Republic of Congo President Joseph Kabila in Kinshasa, Matadi and the southwestern city of Boma, witnesses and security sources said.

A series of large-scale prison breaks across Congo in the past few months has aggravated insecurity since Kabila refused to step down after his mandate expired in December.

Assailants wearing red headbands characteristic of BDK members staged the attack on the high-security Makala prison but did not make it past the front door, said a witness inside the prison.

“We woke up to the deafening noise of gunshots,” said the witness, who asked to remain anonymous for fear of repercussions. He said he had seen police and soldiers gather several bodies outside the prison walls.

BDK leader and self-styled prophet Ne Muanda Nsemi escaped from prison in May and had called on his supporters to rise up this Monday against Kabila, whom Nsemi accuses of being Rwandan -- seen as a slur and quite commonly used by the president’s opponents.

The group aims to revive the pre-colonial Kongo kingdom, which thrived for centuries around the mouth of the Congo River.

“GET OUT”

BDK demonstrators on Monday held signs that read, “Rwanda for Rwandans. Congo for Congolese. Get out, Kanambe,” using another slur to refer to Kabila.

The sect is one of just many sources of opposition of Kabila that threaten to plunge the vast, mineral-rich central country into chaos. The opposition has called for nationwide strikes on Tuesday and Wednesday.

Fearing further unrest, Congolese authorities on Monday ordered internet capacity be slowed down so that it cannot be used to transmit images via social media.

Police spokesman Pierrot Mwanamputu said in a statement that 12 BDK assailants in Kinshasa, armed with calibre-12 rifles and bladed weapons, were killed by “stray bullets” fired by security forces to disperse them. The attackers killed one policeman.

Two others were killed in the southwestern town of Matadi, where three police officers were also injured, he added.

A security source told Reuters two army officers had been killed in Kinshasa while the city’s police commissioner General Sylvano Kasongo told Reuters no one escaped from the prison.

Around 4,000 prisoners, including Nsemi, escaped from Makala in May during an attack by suspected BDK members.

The mounting unrest has led some of Kabila’s allies to call for a state of emergency. More than 50 people were killed on Friday in the southeast in inter-ethnic clashes, part of rising militia violence across the country.