Hundreds of Sudanese protesters took to the streets of the capital Khartoum Monday to demand the ouster of President Omar al-Bashir. Students, activists and other protesters frustrated with economic hardships have held almost daily demonstrations across Sudan since December 19, calling for Bashir to step down. Anger has been brewing for years in the east African country over financial woes, with demonstrators accusing Bashirs administration of mismanaging the economy. Police used tear gas on Monday to disperse hundreds of students from Eastern Nile University protesting in Khartoum North, and hundreds of other demonstrators on Sitteen Street, which runs through several upscale neighborhoods, witnesses said. "Protesters are chanting freedom, peace, justice," a witness said, referring to a slogan that has become the movements catchcry against Bashirs rule. "Who killed our martyrs?" asked protesters as they gathered in Street 60 area, a witness told AFP. Officials say 31 people have died in violence during the protests so far, but Human Rights Watch has put the death toll at 51, with medics and children among those killed. The campaign against the veteran leaders administration was initially led by the Sudanese Professionals Association, a group of teachers, doctors and engineers. Several political parties have since joined the SPA to form an umbrella network called the Alliance for Freedom and Change, which is now leading the campaign. Bashir, 75, has remained defiant and imposed a nationwide state of emergency on February 22 to quell the protests after an initial crackdown failed to rein in the movement. A slew of measures accompanied the state of emergency, including a ban on unauthorized rallies, the setting up of special courts to investigate violations and more powers granted to the security forces to carry out raids without warrants. Bashir also dissolved the previous federal government and installed a new cabinet tasked with tackling the worsening economic crisis. The protest campaign is seen as the biggest challenge Bashir has faced since he swept to power in 1989 in a coup. The scale and intensity of protests, however, have shrunk in recent weeks, particularly since the state of emergency came into effect. "The number of protesters are not big these days," said Sawsan Mohamed, 25, who was sentenced to two weeks imprisonment by a special emergency court for taking part in a rally in Khartoum. "I think the violence unleashed by the security forces and lack of leaders on the ground is keeping many protesters away." Several opposition leaders, activists, journalists and prominent protesters are still in detention following the crackdown on protests.