The pressure from Khartoum came on the eve of the last session of high-level talks in Kenya.
"We are hoping this is the last round of talks," government chief negotiator Nadi Ali Nadi said on Sunday after Sudanese Vice-President Ali Usman Taha arrived in Nairobi for the negotiations.
"We hope that we will complete the peace deal," he said.
Taha and Sudan People's Liberation Movement/Army (SPLM/A) leader John Garang will go into head-to-head negotiations on Monday, a week after delegates started discussing details of a permanent ceasefire and security measures in the Kenyan northwestern town of Naivasha.
"We are enthusiastic and we feel that our brothers on the other side [SPLM/A] will be keen to wrap up this whole thing and complete a peace deal," said Nadi.
Africa's longest war
The UN Security Council last month held a special session in Nairobi and extracted a written promise from the Sudan government and SPLM/A rebels to sign the deal ending 21 years of conflict in southern Sudan by 31 December.
"We hope to beat the deadline. Issues that are remaining are not difficult"
Nadi Ali Nadi,
chief government negotiator
"We hope to beat the deadline. Issues that are remaining are not difficult," Nadi added.
More than two years of intense negotiations have already delivered agreements on key issues such as sharing of power and wealth, leaving technical details on the negotiation table, crucial to reaching a final peace deal to halt Africa's longest and bloodiest conflict.
At least 1.5 million people have been killed and more than four million others displaced by the war, which erupted in 1983 when the mainly Christian and animist south took up arms to end domination by the Arabised, Muslim north as Khartoum tried to impose Islamic law (sharia) on the entire country.