Armed men have abducted at least 89 boys in South Sudan, the United Nations children's agency has said.

The incident happened in a camp in the northern city of Malakal that hosts thousands of people displaced by fighting between the army and rebels.

Unicef says the unidentified gunmen went from house to house and seized boys over the age of 12.

Last week, Human Rights Watch accused both sides of using child soldiers, a charge denied by the government.

The South Sudan conflict began in 2013 after President Salva Kiir accused his sacked deputy Riek Machar of plotting a coup.

Mr Machar denied the allegation, but then raised a rebel force to fight the government.

The UN believes 12,000 children were used as child soldiers across South Sudan last year.

About 1.5 million people have been displaced by the fighting and 2.5 million are facing severe food shortages.

South Sudan is the world's newest state, gaining independence from Sudan in 2011.