Sudanese flooded streets after Friday prayers in a fifth day of protests against fuel price hikes that have seen dozens killed, hundreds arrested and calls for the government's ouster.
The price hikes, resulting from the government scrapping oil subsidies, have sparked the largest protests of President Omar al-Bashir's 24-year rule.
Young activists have invoked chants from the Arab Spring to call for the president's downfall and security forces have been accused of gunning down more than 50 people.
Activists had called for stepped-up protests after weekly Muslim prayers, and security forces responded with a massive deployment on the streets of the capital and elsewhere.
Fresh protests erupted in the evening and police again fired tear gas to disperse the demonstrations who have been urged by activists to pour into the streets as well tomorrow.
The interior ministry 600 had been arrested "for participating in acts of vandalism and will be judged next week."
The announcement came after around 2,000 protesters marched in Omdurman, the capital's twin city, chanting anti-army slogans and calling for an end to fuel price hikes, witnesses and an AFP correspondent said.
Police deployed in large numbers and watched from a distance as the demonstrators marched down a main thoroughfare chanting "Down to the army's power" and "No to price hikes."
Soldiers stood guard outside Khartoum petrol stations as long lines of cars waited to fill up after several stations were torched or shut down in recent days.
Internet access which was cut twice this week was working again today.
But schools have been ordered closed until Monday and most shops remain shuttered, deepening the sense of crisis and sending residents scrambling to stock up on supplies.
"I want my family to have what we need because we don't know where this is all going," said Ahmad Hassan, 50, as he stocked up on canned goods.
In an apparent bid to impose a media blackout on the unrest, Sudanese authorities shut down the Khartoum office of pan-Arab satellite channel Al-Arabiya after summoning its correspondent for questioning, the network said.
Authorities also seized or blocked publication of three newspapers, although they are considered pro-government, journalists said.
