Sudan will see an economic crisis after the south secedes in July that could lead to protests and instability as inflation gets worse, opposition leader Hassan al-Turabi said on Tuesday.

South Sudan voted in January to become independent on 9 July in a referendum promised in a peace deal in 2005 that formally ended decades of civil war in the vast African country.

The north, where 80 per cent of the population live, will lose 75 per cent of the country's 500,000 barrels per day of oil production, which is located in the south and is almost the state's only source of income.

Turabi, the leader of the Popular Congress Party, said the loss of oil revenues would be felt after July and worsen economic woes with annual inflation already hitting 16.5 per cent in April.

"Inflation is a very serious problem," Turabi said in an interview, sitting relaxed in his office in Khartoum just two weeks after being released from three months in prison.

"Look at doctors. They do not make enough to buy a car or a house. They go abroad for work, they work in Saudi Arabia," he said, referring to a strike by state-employed doctors in the Sudanese capital on Tuesday.

Security forces arrested Turabi and eight other party officials on 18 January after he called for a "popular revolution" if Khartoum did not tackle inflation, a sensitive issue in Sudan weighed down by years of conflict and a US trade embargo.

Sudan has not seen uprisings like those in Egypt or Tunisia but Turabi said corruption and economic difficulties might drive people to the streets in larger crowds than the sporadic protests seen so far.

"Many people are very angry," he said. "People are now conscious about corruption due to the new media. They see what is happening in Arab countries," he said.

He said Sudan was a fragile country held together along tribal lines where some areas, such as the troubled region of Darfur, could break up in protests inspired by Arab revolutions.

"It might happen," he said. "I am worried that any protest, revolution could lead to chaos because Sudan is decentralised."

He stopped short of calling for street protests but said Sudan needed an "orderly transition" of power to prevent instability.

"We need real freedom, elections. A peaceful transition of power," he said.

Turabi was the spiritual mentor behind the Islamist government of Sudan's president Omar Hassan al-Bashir when it took power in a 1989 coup, but the men later fell out.
Khartoum has long feared Turabi's influence, believing that many of his supporters remain in key positions in the army and security services.

He has been in and out of jail since his split from Bashir's ruling party in 1999-2000.

The government says inflation goes back to the U.S. embargo but Turabi blamed overspending, which could be seen in Darfur where Khartoum is now adding two additional states requiring yet more bureaucracy.

"You add more to the public service," he said, adding that this would lead to more corruption as many employees were appointed based on tribal or political loyalties.
"Money goes to the public service, to corruption."

Analysts expect both governments to agree on sharing oil revenues as the south needs northern pipelines and refineries but Turabi said the new southern state could seek new friends to lower dependency on Khartoum.

"The south is now very cautious... but they can build new pipelines. The Chinese could build them for them in one and half years."