President Dennis Sassou Nguesso's Parti Congolais du Travail (PCT) and former Prime Minister Bernars Kolélas's Mouvement Congolais pour la Démocratie et le Développement Intégral (MCDDI), signed the agreement on Tuesday.
"The parties affirm their will to implement everything to consolidate peace and security in the Pool in order to make possible the organisation of free and fair elections," said Hello Mampouya-Matson, MCDDI spokesman.
The MCDDI is strong in the region, but could only participate in elections in eight out of 24 electoral areas in 2002 due to insecurity because of fighting between government forces and the former Ninja force led by Frédéric Bintsangou, alias Pasteur Ntoumi.
The government and the Comité national pour le résistance (CNR) of Bintsangou signed a peace agreement on 17 March 2003, bringing to an end a series of civil wars that blighted the Pool region between 1998 and 2002.
Years of conflict have turned the area into one of the most isolated, despite the fact that Brazzaville, the capital, falls within its administrative area. According to aid workers, only one doctor exists for every 30,000 inhabitants - six times fewer than in the rest of the country.
Kinkala hospital, which serves an estimated 90,000 people, has only two doctors, according to Etienne Mouanga, the doctor in charge. Qualified medical personnel fear to work in a region where people have not yet been disarmed, he added.
Only 8 percent of the Pool's population, which was estimated at 362,358 in 2005, has access to clean water. Malnutrition is high among children and the rate of school attendance is about 30 percent.
According to aid workers, violence in the region is exacerbated by the flow of arms. A study by the Swiss NGO, Small Arms Survey, published at the beginning of 2006, showed that between 37,000 and 40,000 weapons of all calibres continue to circulate in the country.
On Tuesday, the PCT and MCDDI also committed themselves to consolidate the country's policies based on good neighbourliness and peaceful coexistence.
The elections are due between June and July, but opposition parties, civil society and religious leaders have said they have reservations about the polls.