An influential opposition leader in Sudan has been arrested after calling for a Tunisian-style "popular uprising" to topple the long-standing regime of President Omar al-Bashir.
The call by veteran Islamist Hassan al-Turabi highlighted the precariousness of the Bashir government which is beset by a downward spiralling economy and the overwhelming vote by the south of the country to form a new independent nation.
Mr Turabi was the ideological force behind the Islamist coup that brought General Bashir to power in 1989. He has long envisaged the creation of a hardline Islamic state, but the two men fell out in a power struggle a decade later.
They have also been divided by the conflict in Darfur which saw the President indicted by the International Criminal Court for war crimes. Mr Turabi has a strong support base in Darfur and links to one of the main rebel groups there, the Justice and Equality Movement.
There is mounting speculation in Sudan that Mr Bashir's days in power in Khartoum could be numbered. The support base of the ruling National Congress Party has been eroded by the economic woes of a country reeling from international sanctions and sharp increases in the cost of living.
While some opposition figures in the north of Sudan have blamed Mr Bashir for the loss of the south – which appears to have voted to separate in a referendum held last week – it's the sharp rises in the cost of essentials such as bread and fuel that have led to street protests in Khartoum. Austerity measures in the face of foreign currency controls and sudden spikes in the cost of commodities have drawn student protests and demands for the resignation of officials.
The Tunisian president, Ben Ali, was forced into exile on Friday after three weeks of escalating street protests over government corruption, political cronyism, food prices and other social problems. Mr Turabi, who was arrested at night, had sought to tap into a similar vein of discontent in Sudan.
Rather than violent revolution on the streets of Khartoum it has been economic bungling that has tended to lead to regime change in Sudan.
With a host of recent setbacks for Mr Bashir, some observers believe the former general's grip on power may be fatally weakened.
"He already has the asterisk next to his name that he ruined the economy; now he has a second asterisk as the man who lost the south," said one Khartoum diplomat.