We want the parties to honestly commit themselves to stop attacking innocent civilians

US State Department spokesman Richard Boucher

Sudanese Deputy Foreign Minister Mutraf Siddeeq said the accord also included the protection of civilian infrastructure.

Signing the deal in the capital, Khartoum, Mr Siddeeq described it as a gradual process for stopping the 18-year conflict.

At the same time, the rebel Sudan People's Liberation Army signed the accord in the Kenyan capital, Nairobi.

US State Department spokesman Richard Boucher said simply getting signatures was not the main aim.

"We want the parties to honestly commit themselves to stop attacking innocent civilians," he said.

Suspension

The agreement is part of measures proposed by John Danforth

The agreement is part of a peace initiative led by former US Senator John Danforth, which also includes a ceasefire in the south-central Nuba mountains and the creation of "zones of tranquility" to allow aid delivery.

But US mediation efforts were suspended last month after the Sudanese Government bombed civilians at a humanitarian relief point.

Some two million people have died in fighting between the Muslim government in Khartoum and the mainly Christian and Animist rebels in the south, who want autonomy and religious freedom.