KHARTOUM, Dec. 29 (Xinhua) -- The Sudanese National Assembly (parliament) approved the law of referendum on self-determination for southern Sudan on Tuesday after the ruling partners struck a deal on disputed issues.

The two major partners in the government, the National Congress Party (NCP) and the Sudan People's Liberation Movement (SPLM), agreed to introduce two amendments into the law.

The first stipulates that all southern Sudanese born since January 1956 should have the right to vote at any voting center whether in southern or northern Sudan.

The second stipulates that holding consultations between the NCP and the SPLM before the referendum on the arrangements for the post-separation period of southern Sudan if the southerners opt for independence in the 2011 referendum.

Yassir Arman, head of the SPLM parliamentary bloc, expressed the SPLM satisfaction over the amendments adopted by the parliament, saying "we have managed to overcome a great barrier. With this, we enter a new important phase."

Speaking to reporters following the parliamentarian session, Arman urged northerners and southerners to work together to achieve a voluntary unity between north and south Sudan.

"As of today, we should work together, southerners and northerners, to achieve a voluntary unity without coercion," he said

"There is a great work that is still awaiting us to build a strong Sudan to be a model for the Arabs and Africans to follow suit," said Arman, adding that "we should prepare the atmosphere so that Sudan would remain united, and we should respect the will of the southerners if they opt for separation."

The Sudanese parliament last week endorsed a bill of the 2011 referendum, though the SPLM and other parties withdrew from the parliament session in protest against the amendments on the bill.

In an attempt to overcome the rift, the two sides decided to return the law to the parliament.