Khartoum: Sudan's Parliament has passed a law on cancelling the Sudanese nationality of southerners, four days after their homeland declared independence from the north, state media reported.

"All the southerners are going to lose their Sudanese nationality directly" because of the amendments to a law approved by the Parliament, MP Ismail al-Haj Musa told a news agency.

Despite a mass migration back to the south since October -- some 360,000 are already thought to have returned -- more than one million southerners remain in the north, according to the UN refugee agency UNHCR.

Many of those remaining were born in the north. Under the amendments, which await a final reading next Monday, "Sudanese nationality is automatically cancelled for any person acquiring the nationality of the state of South Sudan," a news agency reported.

Musa, who belongs to Sudan's ruling National Congress Party, explained that, due to the registration for January's independence referendum, in which southerners voted overwhelmingly to split with the north and forge their own nation, the national identity of southerners had been

More than 99 percent of those voting in the south opted for independence. But only 58 percent of southerners in the north did so, with many concerned about the implications of secession for their work and residency status.

Prior to southern independence last Saturday, the Khartoum Government had already ruled out the possibility of dual nationality for southerners remaining in the north, and dismissed all those working in the public sector.