A solider has been killed while trying to protect protesters outside Sudan's military headquarters in Khartoum, activists say.Clashes have broken out after Sudanese security forces in pick-up trucks used live fire, rubber bullets and tear gas to disperse an anti-government sit-in outside the compound, according to the Sudanese Professionals Association (SPA), which is spearheading the demonstrations.Thousands of people rallied in front of the military headquarters over the weekend in one of the biggest demonstrations since protests erupted in December.The protesters set up tents on Saturday in what appeared to be an effort to replicate the mass sit-ins of the Arab Spring uprisings of 2011.Image:Sudanese protesters are calling on the country's president to step downImage:Demonstrators have gathered outside the country's military headquarters in the capital KhartoumActivists are calling for President Omar al-Bashir to step down.The North African country's government is facing protests due to mismanagement of Sudan's economy.Food prices are soaring and there are regular shortages of fuel and foreign currency.Protesters said security forces, mostly from the feared National Intelligence and Security Service, have been using force to disperse demonstrations.The Sudan Doctors Committee, an affiliate of the SPA, said a soldier was wounded while trying to protect the protesters and later died of his wounds.The medical group said another man died elsewhere in Khartoum after being beaten and tortured by security forces.Footage posted online by activists showed soldiers in uniform moving peacefully among the protesters, raising the possibility that some troops were intervening to halt the violence.Image:A video still purported to show a soldier embracing demonstratorsThe army stepped in to prevent clashes between protesters and police, ultimately forcing President Hosni Mubarak from power, during the 2011 uprising in neighbouring Egpyt.It is unclear whether such a scenario is under way in Sudan, where media access to the demonstrations has been heavily restricted.The protesters have adopted Arab Spring slogans, chanting: "The people want the fall of the regime."Amal el-Zein, an activist, said soldiers guarding the compound stood by at first, but then moved in to chase the security forces away, firing in the air.Image:President Omar al-Bashir faces calls to resignAnother activist said security forces later repeated their attempt to break up the sit-in, forcing protesters to seek shelter in a nearby navy facility.He said the military has deployed troops around its headquarters and blocked several roads leading to the complex.Mr al-Bashir seized power in 1989 in an Islamist-backed military coup.He has refused calls to step down and has appointed military officers to senior posts in an apparent attempt to close ranks.Mr al-Bashir has also declared a state of emergency and presided over a violent crackdown in which dozens of people have been killed.The protests gained momentum last week after Algeria's President Abdelaziz Bouteflika, in power for 20 years, resigned in response to weeks of similar protests.