KHARTOUM, Sudan (CNN) -- Sudan asked the United Nations to stop the United States and other countries from "obstructing" the peace process with southern rebels, the official Sudan News Agency reported on Tuesday.

President Omar Hassan al-Bashir made the request during a meeting on Monday with Kieran Prendergast, the U.N. undersecretary-general for political affairs, it said.

"General Bashir called on the U.N. to convince the sides that are obstructing the peace process and who are working to prolong the war, at the head of which is the United States and some countries in the region, to stop interfering," the agency said.

It did not name the countries but Sudan has previously accused Uganda, Eritrea and Ethiopia of supporting the Sudan People's Liberation Army (SPLA) guerrillas.

Prendergast's trip to Kenya and Sudan this month is one of the few U.N. missions to focus on the politics of the civil war, rather than aid.

Prendergast said the United Nations was not starting a new peace initiative but was working to boost the efforts of the Inter-Governmental Authority on Development (IGAD), a grouping of seven regional African states, which is the only forum to bring the combatants together.

Sudanese government officials and the SPLA rebels have said the IGAD mediation is making slow progress. The last round of talks in Ethiopia made little headway and the next meeting is set for February 1999.

The government and the rebels agreed in October to extend a Cease-fire until mid-January in the Bahr El-Ghazal area, the scene of some of the most intense fighting.

Sudan's war, one of the longest conflicts in Africa, pits the mainly Muslim, Arab north against rebels who want autonomy for the mainly Christian and animist south.

In a move that could signal at least some degree of democratic reform, Sudan's parliament approved a bill allowing the return of the multi-party system to the country after a nine-year ban, newspapers reported on Tuesday.

"The bill was passed (on Monday) by the majority of the members of parliament and no major amendments were made," the government-owned Al-Anbaa daily said.

Al-Bashir is due this week to sign the bill into law, which will become effective on January 1, 1999.

Bashir banned political parties, trade unions and other groups after taking power in a 1989 coup.

Independent dailies said some members of parliament walked out of the session in protest because they had not been given enough time to consider the bill, approved by cabinet last month.

The bill permits a minimum of 100 eligible voters to form a "political association" and to secure financing from any source inside Sudan.

Earlier this month, parliament passed a bill forming a constitutional court, as part of the government's declared plan to restore democracy to the country.

Reuters contributed to this report.