Rebels in South Sudan attacked a town in an oil-producing state on Saturday, killing 15 people, including nine soldiers, and wounding 18, officials said, in the latest violence in Africa's newest nation.

South Sudan became independent in July after a 2005 peace deal with Khartoum that ended decades of civil war, but the new nation has been struggling to end tribal and rebel violence that has killed around 3,000 people this year.

Rebels loyal to Matthew Pul Jang and other militia leaders attacked Mayom in the west of the oil-producing Unity State, Unity Information Minister Gideon Gatpan Thoar told Reuters.

We got attacked in Mayom town today by the militias from 6 to 7 a.m. The militia attacked the town, killed 15 and wounded 18, Thoar said. More than 60 militiamen were killed.

Army spokesman Philip Aguer said: It was indiscriminate, they didn't differentiate between civilians and the army. The killing included a doctor.

The rebels could not immediately reached for comment.

Violence threatens to turn South Sudan into a failed state, undermining the stability of its east African neighbours. Several rebel militias are fighting government forces in remote parts of the country, which is roughly the size of France.

South Sudan has accused Khartoum of supporting militias but the north denies this, and many rebels say they are fighting against what they see as corruption and ethnic discrimination in the south's government, charges Juba denies.

(Reporting by Hereward Holland; Writing by Ulf Laessing; Editing by Alistair Lyon)