South Sudan rebels threaten to stall peace talks

South Sudan rebels threatened to stall peace talks aimed at ending nearly two months of fighting, demanding the release of detainees and the withdrawal of foreign troops, the opposition said Monday.

"We are abstaining from participating in the next round of peace talks," Taban Deng, head of the opposition delegation, said in a statement.

Deng demanded the release of four detainees who remain in prison following the release of seven of their colleagues in late January.

He also called for the immediate withdrawal of Ugandan troops, who have been in the country at the request of South Sudanese president Salva Kiir since the conflict erupted on December 15.

The warring sides signed a fragile ceasefire last month to end weeks of violence that has left thousands dead and displaced 900,000 people in the world's newest nation.

The second round of talks, aimed at reaching a long-term political solution, was set to open Monday but was delayed for logistical reasons. Officials said the talks would open Tuesday instead.

The chief mediator from the regional bloc IGAD condemned the rebels for opposing a precondition on the talks, which he said was in violation of the agreement signed on January 23.

Blocking the talks "would be tantamount to holding hostage the people and the nation because of those demands," Seyoum Mesfin told reporters.

The issue of 11 political detainees arrested after fighting erupted in December has been a major sticking point in the talks since they opened in Addis Ababa last month.

The seven released are set to take part in the new negotiations as a third party independent of government and opposition delegations, according to Seyoum.

Despite the ceasefire signed last month, fighting has continued in the oil-rich but impoverished country, which gained independence from Sudan in 2011 after a bloody civil war.