Liberian President Moses Blah has returned home from peace talks in Ghana without reaching an agreement with rebel leaders.
Mediators had hoped to sign a deal Saturday to set up an interim government that would take over from Mr. Blah in October and then run the country for two years until elections can be held.
Sources close to the talks say the negotiations broke down over rebel demands for top positions in the government. They say the rebels insist on having the posts of vice president and speaker of parliament in the interim government.
The AFP news agency quotes a LURD rebel official as saying the rebels will resume fighting if their demands are not met.
Meanwhile, a second group of Nigerian peacekeeping troops arrived in the Liberian capital, Monrovia, bringing the total number of peacekeepers in the country to nearly 1,000.
Rebels formally conceded control of Monrovia's port Thursday to peacekeeping troops, after Charles Taylor resigned as president and left the country earlier this week.
Aid workers in the capital are appealing for equipment to distribute much needed food and medicine throughout the city.
The U.N. envoy to Liberia Jacques Paul Klein says because of the critical humanitarian situation in Liberia, he is urging the United Nations to lift sanctions on the country.