South Sudanese rebels attacked the capital of oil-producing Upper Nile state on Tuesday, Feb 18, a spokesman for the regional administration said, the first fighting in a provincial capital since rebels and the government signed a ceasefire in January, Reuters reports.

Rebel forces could not immediately be reached for comment, but President Salva Kiir's government and rebels loyal to former vice president Riek Machar have both accused the other of violating the January 23 ceasefire deal signed in Ethiopia.

"The fighting is continuing, but our forces are still in control of Malakal," Philip Jiben, spokesman for the Upper Nile administration, told Reuters by telephone. Gunfire could be heard in the background as he spoke.

A UN official said he had received reports of fighting in Malakal but could not confirm them. The town fell into rebel hands after fighting first broke out in mid-December before government forces recaptured it last month.