Gration will travel to Khartoum, the capital, as well as the Sudanese towns of Juba and Boma and to the violence-plagued western region of Darfur, the state department said.

The discussions are timed to take place before the country's first democratic election in more than 20 years, due in February.

'Lasting peace'

Gration told Al Jazeera: "We hope to reach a way ahead so that we can move forward on these critical issues because the census is critical to the election and of course the referendum is that vote that will decide whether the south remains united as one country.

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"We are working right now to unify the rebel groups, to give voice to the civil society, and then to enter into the process in Doha.

"[There] we will come together and reach a peace agreement that will be durable, that will be lasting and will allow the people to have dignity, the respect, the security, the stability and the economic prosperity that they deserve".

The SPLM fought against northern Sudanese forces in a two-decade civil war, which was supposed to end with a 2005 peace accord that created a semi-autonomous government in the south.

Northern and southern armies have clashed on several occasion since the 2005 agreement, most recently last year in the central oil region town of Abyei, claimed by both the north and south.

The fighting is separate from the conflict in Darfur where United Nations officials say as many as 300,000 people have died and more than 2.7 million have been driven from their homes in nearly six years of ethnic and political violence.

Gration, a retired air force general with broad experience in the region, was appointed by Barack Obama, the US president, in March to lead Washington's efforts in tackling the deteriorating humanitarian situation in Darfur.