Leading article: Africa has a moment of hope – and peril

The world is about to welcome its newest country, the Republic of South Sudan.

There will be much celebration, and rightly so. Africa gains its 54th nation, one born of half a century of civil war, in which some two million people have died.

Today's formal declaration of independence corrects a massive historical and ethnic injustice. For decades, the black African and largely Christian south of the country was marginalised and repressed by the Arabic and Islamic north. An internationally guaranteed peace agreement was reached in 2005, and in a referendum in January 99.5 per cent of southerners voted for secession. "Free at Last," proclaims the count-down clock in South Sudan's capital of Juba.

Alas, the hard part is surely only starting. "We will bless our brothers in the south over their country and we wish them success," declared Omar al-Bashir, who has spent most of his 22 years as Sudan's president employing violence to hold his sprawling country – Africa's largest – together. His government has recognised its new neighbour and the president is attending today's ceremony. His promise of non-interference in South Sudan's affairs will however, soon be put to the test.

The new country, one of the very poorest on earth, must be built from scratch. Most of its people live on less than $1 per day, while the illiteracy rate is 75 per cent. It has fertile land and above all oil reserves, but an equitable deal on sharing oil revenues has yet to be reached with the North, through whose territory the export pipelines mostly flow.

That will be one test of the sincerity of Mr Bashir, who is wanted by the Internatial Criminal Court for atrocities allegedly committed on his orders in Darfur. Another is the continuing dispute over several of the border regions, notably South Kordofan and Abyei, where fighting has killed 2,300 people so far this year alone and where in the words this week of US ambassador to the UN Susan Rice, a "grave humanitarian situation" exists.

Thorny issues of citizenship are still unresolved. An official frontier has yet to be agreed, and various rebel groups roam over swaths of the new country. Failure to resolve these issues could reignite the conflict between north and south.

That the Republic of South Sudan exists at all is largely the result of outside pressure and international vigilance. A robust and sustained United Nations presence, including for a transitional period in Sudan, will now be required. Despite the bad omens, this frail new creation represents a moment of hope for Africa. We must not allow it to crumble.