KINSHASA (AFP) - A humanitarian catastrophe is unfolding in DR Congo's Katanga province, where rebel violence has destroyed 600 homes over the past three months and displaced 400,000 people, the UN said Wednesday.

The head of the world body's MONUSCO mission in the Democratic Republic of Congo admitted that the huge southeastern province had been neglected in recent months.

"It's a humanitarian catastrophe," Martin Kobler told reporters in Kinshasa, referring to the situation in Katanga, where violence has spiked recently.

"I feel an element of guilt when I think of Katanga because we have concentrated our military activity on the Kivus but it is important not to neglect Katanga," he said.

Late last year, the UN's peacekeeping mission in the restive country deployed an unprecedented intervention brigade to stamp out the M23 rebellion in the northeastern province of North Kivu.

The focus on the M23 and subsequently on other armed groups operating in the same region created a security vacuum in Katanga, the country's wealthiest province.

Katanga, which at almost half a million square kilometers is about the size of Spain, is believed to hold around a third of the world's cobalt and 10 percent of its copper reserves.

Its capital Lubumbashi is the country's second largest city and the province has been plagued by secessionist violence since DR Congo's independence from Belgium in 1960.

Over the past year, rebel groups fighting for Katanga's independence -- known as Mai Mai Bakata Katanga -- have sown terror in the province's northern regions.

"Most affected is the area between Manono, Mitwaba and Pweto where more than 600 houses in 11 villages have been destroyed since October last year," the UN said in a statement.

The area is known as the "triangle of death" and the UN said other armed groups were also active there.

"All armed groups must stop their activities and allow humanitarian access to the main victims of this tragedy, the civilian populations," Kobler said.

MONUSCO said there were an estimated 400,000 internally displaced people in Katanga, a figure that marks a "dramatic increase" over two years.

Mai Mai Bakata Katanga launched brazen attacks that left dozens of people dead in Lubumbashi in March and November 2013.

Following attacks earlier this month on strategic buildings in the national capital Kinshasa -- 1,000 miles to the west -- the Mai Mai rebels intensified their activity around Lubumbashi, forcing civilians to flee.