The M23 rebel group has threatened to pull out of peace talks with the Democratic Republic of Congo government unless President Joseph Kabila signs a ceasefire agreement.
Talks are due to start in the Ugandan capital, Kampala, on Friday.
A Congo government spokesman told the Reuters news agency it rejected a rebel demand he described as "pointless".
A first attempt to negotiate an end to the nine-month rebellion in the east of the country failed last month.
As many as 800,000 pe