Congolese President Joseph Kabila is meeting his election rival, Jean-Pierre Bemba, for the first time since their forces clashed in August.
Joseph Kabila (l) faces Jean-Pierre Bemba (r) in October's run-off
There have been intense diplomatic efforts to bring the two men together.
European Union foreign policy chief Javier Solana and South African leader Thabo Mbeki have visited, appealing to them to settle their differences.
The fighting in the capital, Kinshasa, left 23 people dead and raised fears of violence in the run-off on 29 October.
In July's first-round of voting for a new president, Mr Kabila took 45% of the vote, just short of the 50% needed for victory, while Mr Bemba gained 20%.
The election was the first democratic poll to be held in the country since it gained independence in 1960 and follows the official end of a five-year conflict.
Mr Bemba is a former rebel leader and retains his own personal security force. The presidential guard is widely regarded as Mr Kabila's personal force.
The polls are meant to put an end to a transition process established after five years of war that ended in 2003.
The world's largest UN peacekeeping force has been trying to help the former combatants disarm and form a unified army.