Cairo - Riot police fired tear gas and civilians armed with machetes and swords attacked protesters during five days of demonstrations sweeping Khartoum demanding ouster of Sudan's autocratic ruler, said a Sudanese opposition leader.
Saata Ahmed al-Haj, head of the opposition Sudanese Commission for Defence of Freedoms and Rights, said that hundreds of protesters have been detained over the past five days. He said they were later released but were badly mistreated.
Al-Haj said security forces shaved off the protesters' hair, stripped them naked, flogged them and then left them outside in the scorching sun for hours.
"I am under house arrest along with several opposition members, and security forces are encircling the place," he said by phone. "Our 'offense' is we are searching for freedom, and this is a crime in Sudan," he said.
"This is the outcome of political, economic and military suffocation felt by people here," al-Haj said.
A government austerity plan slashing subsidies and doubling price of fuel and food set off the protests. President Omar al-Bashir has said the measures are necessary to pay for his country's conflict with South Sudan and to replace Sudan's oil revenues. He said Sudan no longer exports oil.
On Thursday, al-Bashir issued new decrees to cut expenditures as "part of the austerity plan", according to Sudan's official news agency Suna.
The demonstrations started on Saturday night at the University of Khartoum. Students protesting transportation fare hikes took to the streets outside the downtown campus, where security forces fired tear gas and rounded up dozens of them.
Since then, Khartoum has been the scene of daily protests, spilling out to different of the capital.
Echoing calls heard in Arab Spring uprisings in Tunisia, Egypt, Libya and Syria, protesters chanted: "The people demand to bring down the regime."
Al-Bashir, 68, has ruled Sudan since 1989, when he carried out a bloodless military coup. Sudan was then in midst of two decades of civil war with the south, which declared independence in 2011 and became the nation of South Sudan.
In the wake of another conflict, this one in the Darfur region in western Sudan, al-Bashir became the first sitting head of state indicted by the International Criminal Court for war crimes and crimes against humanity.
In the Khartoum protests this week, at least one journalist was held by authorities for questioning and then released.
Salama el-Wardani, an Egyptian journalist who works for the Bloomberg news agency, told the Egyptian daily al-Masry al-Youm that she was detained and interrogated for five hours along with a Sudanese activist, Maha al-Senousi. The two were arrested while covering protests at Khartoum University on Thursday.
The New York-based Committee to Protect Journalists urged authorities to stop harassment of journalists. Spokesperson Rob Mahoney said in a statement that "journalists should be allowed to carry out their work freely without the threat of arrest".