Sudanese President Omar al-Bashir has reassured Southern Sudan he will help it even if it chooses to secede in a referendum on Sunday.After arriving in the south's capital, Juba, Mr Bashir said that although he would be "sad" if Sudan split, "I am going to celebrate your decision, even if your decision is secession."
Mr Bashir then headed into talks with the south's leader, Salva Kiir.
The referendum is part of a 2005 deal that ended a two-decades-long war.
Mr Bashir and Mr Kiir were on opposing sides.
Officials say almost four million people have registered to vote, more than 95% of them in semi-autonomous Southern Sudan. Others have signed up in northern Sudan and eight countries abroad.
'Anything you need'
BBC East Africa correspondent Will Ross, in Juba, says Mr Bashir's message on Tuesday will go a long way to reassure people that the north of Sudan is finally accepting that Africa's largest country is about to split in two.
Mr Bashir said: "I personally will be sad if Sudan splits. But at the same time I will be happy if we have peace in Sudan between the two sides."Saying that imposing unity did not work, he added: "Anything you need in terms of technical, logistical or professional support from Khartoum, you will find us ready to give it. The benefit we get from unity, we can also get it from two separate states."
Our correspondent says that for years Mr Bashir was seen as an enemy in the south but his message on Tuesday, a message of peace, may help to improve his tarnished image.
Mr Bashir, wearing a traditional southern robe over his suit, was met by about 500 people at the airport in Juba demonstrating in favour of secession, but in a festive atmosphere.
He and Mr Kiir then went into talks that were to focus on weighty issues such as border delineation, citizenship and division of oil wealth.
Sudan is the third-largest oil producer in sub-Saharan Africa.
'100% prepared' Southern Sudan has been marginalised by a succession of governments in Khartoum, from colonial times onwards.
The north and south are also divided by culture, religion, ethnicity and a history of conflict, correspondents say.
On Monday, a spokesman for the Southern Sudan Referendum Commission (SSRC), Chan Reec Madut, said it was "100% prepared" for the vote.
Some training still needed to be carried out and there were still problems with access to polling stations in remote areas, he said. But he insisted that those would not affect the vote.
There had been concerns that Sudan's poor infrastructure and political instability might delay the referendum, risking an outbreak of violence.
For the vote to be considered valid, 60% of voters must take part.
A spokesman for the US state department, PJ Crowley, said it was optimistic about Sunday's referendum, and that both sides appeared to agree that it should be an open and credible process.