KINSHASA – Security in Congo's copper-mining heartland of Katanga is a "very serious concern" that must be tackled politically and militarily, the outgoing head of the UN peackeeping mission said on Monday.

The province, which sits on some of the world's largest copper reserves, last year exported 600 000 t. Miners including Freeport McMoRan and Glencore already operate there.

In March, hundreds of rebel fighters attacked the Katangan capital of Lubumbashi and then surrendered following bloody clashes with security forces. On Sunday, a soldier was killed during fighting between the army and insurgents 20 km from the city.

"It's a quite significant problem, and I think it has all the prospects of becoming worse," Roger Meece, the head of the UN's peacekeeping mission in Congo, known as MONUSCO, said.

"One can do what is possible militarily and or with a police force but ... the real solutions have to be found in these political factors," Meece, who is leaving his post later this month, said in an interview.

Meece said fears that the province would be broken up were feeding the tension.

"Probably it's related at least in part to people looking towards future election cycles, both provincial and national," he added.

Katanga has long had a fractious relationship with the central government in Kinshasa and attempted to secede directly after independence in 1960.

More recently, provincial and national leaders have clashed over management of the mining industry and its revenues. Katanga's governor earlier this year refused to implement a decision by Kinshasa to ban the export of copper concentrate.

Katanga is also the home province of President Joseph Kabila and some of his prominent allies. Analysts have said that growing splits within the ruling coalition could be behind the recent upsurge in violence.

On Sunday, one soldier died after clashes with the Bakata Katanga rebel group, according to government spokesman Lambert Mende, who said the authorities were investigating who or what was behind the growing insecurity.

"We don't have proof and we don't want to accuse anyone unfairly, but we want to find out what is behind this. Politicians or not, these are still crimes," he said.

Earlier this month UN-backed broadcaster Radio Okapi reported that 13 women, eight of them pregnant, were burnt alive by rebels in the north of the vast province, which is the same size as France.

But the province's business-friendly governor said such media reports had blown the security problem out of proportion.

"There's no problem in the province, everything is going well," Moise Katumbi said by telephone.

"No leaders in Katanga are going to support these (rebels). We have to give confidence to investors," he added.