Two UN officials have been kidnapped in the Democratic Republic of Congo, the government says.

Michael Sharp, a US man, and Zaida Catalan, a Swedish woman, were taken by unknown assailants on Sunday, according to a UN official.

The pair were taken along with four Congolese support staff into the forest near the village of Ngombe in Kasai Central province, the official said.

Search parties have been sent out to look for the group.

A rebellion against the central government of DR Congo broke out in the Kasai region last year.