Egypt's foreign minister said a break-up of Sudan looked inevitable because northern and southern officials had made no real effort to keep Africa's biggest country united.
A referendum on independence for south Sudan, promised under a 2005 Comprehensive Peace Agreement (CPA) that ended decades of civil war, is due to take place on 9 January, but preparations are falling behind schedule.
"Since the signing of the CPA there have not been real or serious efforts from either side to remain together," Egyptian Foreign Minister Ahmed Aboul Gheit said in an interview broadcast on state TV late on Saturday.
"All indications point towards an inevitable separation," he added.
Southern leaders have been making increasingly separatist statements and analysts say most southern Sudanese, embittered by the civil war and perceived northern exploitation, are expected to choose independence.
The north's dominant National Congress Party, led by Sudanese President Omar Hassan al-Bashir, is campaigning to persuade southerners to choose unity.
Disagreements remain over key issues such as security, the border and the fate of the oil-producing Abyei region straddling north and south.
Egypt proposed a looser confederation last month as an alternative to secession, and Aboul Gheit said Egypt would not object to a referendum delay of several months.
US embassy documents published last week by Wikileaks showed Egypt lobbied last year to delay the secession vote by four to six years, fearing an independent south would fail and the division would threaten Egypt's access to Nile water.
Wikileaks published another US embassy cable from April 2009 quoting Egypt's spy chief, Omar Suleiman, as telling Admiral Mike Mullen, chairman of the US military's Joint Chiefs of Staff, that "Egypt does not want a divided Sudan".
"Egypt spoke to both sides to make unity an attractive (option) and has tried to convince both parties to resolve their differences before the referendum of 9 January ", Aboul Gheit said.
