Thousands of demonstrators took to the streets Thursday in cities across Sudan, including the capital, where activists said two people were killed in clashes between police and protesters attempting to reach the presidential palace to demand longtime ruler Omar al-Bashir step down.The protests, called for by professional and opposition groups, are part of a wave of unrest over a failing economy that has transformed into demands for the resignation of the autocratic al-Bashir, an Islamist who has run the country for nearly 30 years but brought little improvement to his people. The protests first erupted on December 19."Day after day, the number of demonstrators is increasing. Today we will gather in the thousands and tomorrow we will reach the millions," said Reem, a 35-year-old receptionist demonstrating in Khartoum. "I will not stop until we achieve the change that gives me a decent life, a job and the salary I deserve."Mohammed Yousef, a spokesperson for the Sudan Association of Professionals, said protesters were prepared to continue to press their grievances while remaining "patient and wise"."The people of Sudan are known for being particularly determined, stubborn, and for playing the long game. They are not hot-headed, nor do they despair easily," he said.The government crackdown has been harsh over the past month, with rights advocates reporting the use of excessive force by police and Amnesty International accusing security forces of firing tear gas and live ammunition in and around hospitals. At least 40 people have been killed in the clashes, according to rights groups, but the government has acknowledged only 24 deaths.'Freedom of association'The UN High Commissioner for Human Rights Michelle Bachelet called such reports "credible" and "deeply worrying", urging the government to ensure citizens' rights to freedom of expression and peaceful assembly, regardless of their political affiliations, according to Sudan's international treaty commitments."A repressive response can only worsen grievances," she said.Bachelet said the UN would be ready if asked to deploy a team to Sudan to advise authorities "and help ensure they act in accordance with human rights obligations."At a UN Security Council meeting in New York on sanctions against Sudan, Western nations expressed concern at the government's response to the protests.US political coordinator Rodney Hunter urged the government "to respect the rights to freedom of association and peaceful assembly, to release all journalists, political opposition leaders, activists, and any other protestors arbitrarily detained" — and to ensure an independent and transparent investigation into the deaths of protesters.Sudan's UN Ambassador Omer Dahab Mohamed responded that the government "is fully committed to giving citizens a space to peacefully — I repeat peacefully — express their views on the political and economic situation of their country."At the same time, he said, the government is also committed to its constitutional duties under international law "to protect lives and public property against sabotage and arson and all other forms of violence perpetrated by some demonstrators."Hundreds of demonstrators aged in their 20s and 30s gathered in the back streets around the Nile-side presidential palace, calling for a peaceful uprising and the downfall of al-Bashir, while men in civilian clothing carrying assault rifles — some wearing face masks — blocked the main approaches, activists said.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook. Videos posted online — the main method to communicate freely in Sudan — showed several marches in the hundreds across the country, with activists claiming nearly 2,000 demonstrators were in central Khartoum and two dozen of its neighborhoods held their own protests. They also circulated photos showing several demonstrators purportedly injured by live fire.As in previous attempts, police Thursday prevented the protesters from reaching the palace in Khartoum, using tear gas, rubber bullets and firing live ammunition in the air to disperse them. Cat-and-mouse maneuvers later ensued between the police and the protesters, who remained on the streets well after nightfall.Smaller protests later erupted in residential neighborhoods and the activists reported that the security forces were storming homes to arrest protesters who took refuge there.A medical committee associated with the protests' organizers said two demonstrators, including a child, died of gunshot wounds. Four others were wounded when hit by live rounds and three more sustained injuries from rubber bullets.The casualty figures could not immediately be independently confirmed.Earlier in the day, security forces arrested several journalists near the palace who were reporting on the march, they added, while police fired tear gas to disperse crowds elsewhere in the city's central al-Arabi market area.Sudan's economy has stagnated for most of al-Bashir's rule, but its recent lows have been dramatic, with surging prices and a plummeting currency that prompted the protests. He has also failed to unite or keep the peace in the religiously and ethnically diverse nation, losing three quarters of Sudan's oil wealth when the mainly animist and Christian south seceded in 2011 following a referendum.Bashir, who is also wanted by the International Criminal Court for genocide in Darfur, has said those seeking to oust him can only do so through elections. He is expected to run for another term in office in elections next year.