South Sudan says fighting rebels in oil state Upper Nile's capital

"There has been heavy fighting between the forces loyal toDr Riek Machar and the government forces (in Malakal),"presidential spokesman Ateny Wek Ateny told Reuters by phone.The rebels first attacked Malakal on Tuesday morning, he said.

Ateny said Upper Nile oil fields, which produce about200,000 barrels of oil per day, were far away from Malakal andunder government control. "The oil fields are safe," he said.