Sudan's president and vice-president have engaged in a public row during a ceremony to mark the second anniversary of a peace deal to end the civil war.
Salva Kiir is national vice-president
Southern leader Salva Kiir said there were "serious problems" with the deal and accused President Omar al-Bashir's party of backing militias.
A visibly angry Mr Bashir responded in front of a crowd of several thousands by criticising southern officials.
The deal ended 21 years of war between the Muslim north and Christian south.
The agreement to end what was Africa's longest-running conflict, which claimed some 1.5m lives, was widely acclaimed when it was signed after many years of talks and intense international pressure on both sides.
"The [deal] ensured a radical change in Sudanese politics [and] equitable and transparent share of wealth and resources. Has this happened? The answer is incredibly no," Mr Kiir said in a lengthy speech in the southern capital, Juba.
He also accused Mr Bashir's National Congress of supporting militias who still operate in the south, although they were supposed to have been disarmed.
Last November, hundreds of people were killed in Malakal in clashes b between militias and former rebels from the south.
Mr Bashir admitted that parts of the deal had still not been put into effect but he said southern officials had been slow to take up their posts in the various commissions set up to implement the peace deal.
"For six months we waited in Khartoum for our brothers in the [former rebel] SPLM to come," he said in his speech. "In the end we paid $60 million for these people to come."
He said that 30,000 of the 40,000 militiamen active in the south had been disarmed but the job could not be finished overnight.
Sudan analyst Gill Lusk told the BBC Focus on Africa programme that the northern government has a deliberate policy of holding up the peace process.
She says many southerners complain that there has not been enough progress in the past two years - partly because there was no infrastructure or trained personnel in the south after the long war.
Under the power-sharing deal, south Sudan's leader is also national vice-president.
The south is to enjoy six years of autonomy before a referendum on independence.
Oil revenue and government jobs are to be shared equally.
Most of the oil lies in the south but southerners complain that most of the money still goes to the north.
Since fighting ended in the south, a separate conflict has broken out in Sudan's western region of Darfur.