Sudanese police fired tear gas at hundreds of protesters marching towards the presidential palace in Khartoum on Thursday, as demonstrations demanding President Omar al-Bashir's resignation spread to other cities and towns.
Protesters chanting "Freedom, peace, justice" gathered in central Khartoum and began their march but riot police quickly confronted them with tear gas, witnesses told AFP.
Demonstrations were also held in the Red Sea city of Port Sudan, in the provincial town of Gadaref and in the agricultural hub of Atbara, where the first protest broke out in December after a government decision to raise the price of bread.
The protests have since escalated into broader demonstrations against Bashir's three decades of iron-fisted rule that have triggered deadly clashes with the security forces.
Officials say at least 24 people have died, but human rights groups have given a higher toll.
Amnesty International said last week that more than 40 people had been killed and more than 1,000 arrested. Human Rights Watch said the dead included children and medical staff.
Ahead of the protests, an AFP journalist saw security personnel, many in plainclothes, stationed across the downtown area of Khartoum and along the expected route of Thursday's march.
Several army vehicles mounted with machineguns were stationed outside the palace.
Anger over bread price
Little traffic was seen at what is usually the height of the morning rush hour as people stayed off the streets.
The protest movement has been spearheaded by the Sudanese Professionals Association, a trade union representing doctors, teachers and engineers among others, that has stepped into the vacuum created by the arrest of many opposition leaders.
Despite the crackdown, the movement has grown to become the biggest threat to Bashir's rule since he took power in an Islamist-backed military coup in 1989.
The protesters accuse Bashir's government of mismanagement of key sectors of the economy and of pouring funds into a military response Sudan can ill afford to rebellions in the western region of Darfur and in areas near the border with South Sudan.
Sudan has suffered from a chronic shortage of foreign currency since the south broke away in 2011, taking with it the lion's share of oil revenues.
That has triggered soaring inflation that has seen the cost of food and medicines more than double, and frequent shortages in major cities, including Khartoum.
Angry protests flared on December 19 after the government tripled the price of bread.
A defiant Bashir has dismissed calls for his resignation but acknowledged the country faces economic problems for which a slew of reforms were being planned.
The veteran president, 75, has blamed the violence on "conspirators" working against the interests of the country, without identifying them.
Bashir has ordered the police to use "less force" against protesters, but the violence during the demonstrations has drawn international criticism.
UN 'very concerned'
UN High Commissioner for Human Rights Michelle Bachelet on Thursday condemned Sudan's "repressive response" to the anti-government demonstrations.
"I am very concerned about reports of excessive use of force, including live ammunition, by Sudanese state security forces during large-scale demonstrations in various parts of the country since 19 December," she said in a statement.
"A repressive response can only worsen grievances," she warned, calling on Sudan's government to protect the protesters' right to freedom of expression and peaceful assembly, regardless of their political affiliations.
More than 1,000 people including protesters, journalists, opposition leaders and activists have been arrested in a sweeping crackdown by security agents since the protests erupted.
"The government needs to ensure that security forces handle protests in line with the country's international human rights obligations by facilitating and protecting the right to peaceful assembly," said Bachelet.
She called on the government to ensure the immediate release of all those who had been arbitrarily detained.
"I urge the authorities to work to resolve this tense situation through dialogue, and call on all sides to refrain from the use of violence," said the UN rights chief.