|Salva Kiir, the southern Sudanese president, was one of the first to register for the January referendum [AFP]
The UN Security Council has expressed concerns over preparation delays for South Sudan's self-determination referendum.
At a meeting in New York on Tuesday, Ban Ki-moon, the UN secretary-general, said he feared a "wider conflict" between the country's north and south.
The council said in a statement that it was "concerned" over delays by the government in Khartoum releasing funding for the January 9 referendum in South Sudan and the nearby oil-rich region of Abyei.
It called for Sudanese officials to renew efforts to make sure the vote is held on time.
Al Jazeera's Scott Heidler, at the United Nations in New York, said there was an outpouring of international support for the upcoming referendum.
"This is a critical piece of a 2005 peace agreement. This is the culmination of it. It is very important and that has been stated by all the speakers so far at this meeting today.
"Underlined too is pressure to make certain that it happens on time. There are concerns over whether the vote will go on January 9 as scheduled," he said.
At the meeting, Hillary Clinton, the US secretary of state, said it was critical for the referendum to be held on time, warning that the "unacceptable alternative'' is a return to civil war.
Clinton also said there is "a huge amount of work to be done'' in the next 55 days to ensure the vote is not delayed.
Voter registration got under way as scheduled on Monday, but other preparations for the vote are seriously delayed.
The referendum is the final phase of a 2005 peace agreement that ended two decades of war between the Arab-majority north, and the south made up mostly of Christians and animists.
If voters back the south's secession in the referendum, it would split Africa's largest nation into two.
Many worry that problems with the vote could set off violence between the two regions, even a new civil war.
Valerie Amos, the UN humanitarian chief, told journalists on Monday that relief agencies are stockpiling supplies in areas of South Sudan before the vote.
"Work is already ongoing in Sudan to preposition humanitarian assistance near potential hot spots in southern Sudan and in the border areas," Amos, who just returned from a six-day visit to the country, said.
Amos noted concerns that the balloting could prompt a massive return of southerners who had migrated to the north seeking better lives and said a small number of them were beginning to move back to the south.
"But the conditions need to be appropriate and their safety and security must be guaranteed,'' she said.
"Ensuring that the returns take place in a free and principled manner is, of course, the responsibility of the government.''
Source: Al Jazeera and agencies