Crowds of Sudanese protesters chanted "freedom, freedom," as riot police fired tear gas on anti-government rallies in the capital and its twin city of Omdurman on Monday, witnesses said.
They said protesters took to the streets in two districts of Khartoum and in Omdurman, across the Nile.
Riot police swiftly moved in to disperse the protests, firing tear gas at one of the rallies in Khartoum and in the twin city, according to witnesses.
Even as police fired tear gas, protesters kept up the "freedom, peace, justice" rallying cry of an anti-government campaign that erupted in December, witnesses said.
Monday's demonstrations came after campaigners called for new rallies this week against the government of President Omar al-Bashir.
Earlier on Sunday, Bashir pledged to bolster rural development, in a step to face down anti-government demonstrations that have rocked cities and villages.
The veteran leader has been on a charm offensive with rallies across the country in a bid to head off weeks of protests seen as the biggest threat to his 30-year rule.
On Sunday, he traveled across North Kordofan, addressing hundreds of people in three separate televised rallies, including a night-time event in the state capital of Al-Obeid.
In the morning he addressed hundreds of villagers in the day's first rally, promising to bring clean drinking water to rural areas "across Sudan".
The speech came after he inaugurated a new 340-kilometer highway linking North Kordofan to Omdurman, the twin city of Khartoum.
"Building such a road in present economic conditions is not an easy thing to achieve," said Bashir, after being escorted to the stage by dozens of men on camels as crowds of villagers clapped and whistled to Sudanese tunes.
"Along this road we will bring electricity to boost the region's growth."
Hours later Bashir addressed a second rally where he called on the country's young men and women to help develop the country.
"The youth, for whom we have built universities, have to be ready to continue with the mission of building a new Sudan," he said in a village where hundreds had gathered.
The statement came after Prime Minister Moutaz Mousa Abdallah on Saturday called the protest movement a "respectable youth movement" and said its voice should be heeded.
As darkness fell, Bashir, dressed in traditional robe and turban, spoke to hundreds of cheering supporters, including students, at an open-air stadium in Al-Obeid where authorities have renovated an existing hospital.
"Patients often go to England, India or Jordan for surgeries, but now we can do them at Al-Obeid," he said as crowds cheered and loyalists set off fireworks.
Demonstrations erupted in Sudan in December after a government decision to triple the price of bread unleashed frustrations at years of deteriorating living conditions and growing hardship.
Officials say 30 people have died in protest-related violence, while rights group Human Rights Watch says at least 51 have been killed.
Bashir's attempts to rally support have so far failed to halt the wave of discontent, with the group leading the demonstrations calling for fresh protests over the next few days starting Sunday night.
Late on Sunday, a group of protesters chanted "revolution, revolution," in a neighborhood of Omdurman, witnesses said.
Bashir and other senior Sudanese officials have repeatedly said that the government can be changed only through elections.
The leader, who came to power in a coup in 1989, is considering running for a third elected presidential term in polls due next year.