Some groups called for "dictator" Ortega and his wife to step down, yelling "Out! Out!" Mass street protests are rare in Nicaragua, where the army maintains a very tight grip on public order. MANAGUA: The United Nations said Tuesday that many deaths in nearly a week of anti-government protests violently repressed by police in Nicaragua may have been "unlawful" and called for an investigation. The scrutiny from the Swiss-based UN human rights office adds to international alarm at Nicaraguan President Daniel Ortega"s ordered crackdown against a wave of anti-government demonstrations and clashes. The European Union, United States and the Vatican have all urged talks to restore calm, while the US embassy in Managua ordered family members of staff out of the country after Ortega deployed the army to the streets and looting broke out. A toll compiled from the Nicaraguan Center for Human Rights and Ortega"s wife and vice president, Rosario Murillo, puts the number of deaths since last Wednesday at 27. Most were protesters, among which university students and youths figure prominently. "We are particularly concerned that a number of these deaths may amount to unlawful killings," Liz Throssell of the UN Office for the High Commissioner on Human Rights told reporters in Geneva. "It is essential that all allegations of excessive use of force by police and other security forces are effectively investigated to ensure those responsible are held to account," Throssell said. The UN office said at least 25 people, including a police officer, had been killed. The protests were sparked Wednesday by pension reforms aimed at keeping Nicaragua"s burdened Social Security Institute afloat by cutting benefits and increasing contributions. But they rapidly spread and intensified as other grievances over Ortega"s rule surged to the fore. On Monday, tens of thousands of people -- employees, students, pensioners and ordinary citizens -- marched peacefully in the capital Managua and other cities demanding an end to the forceful security crackdown on protests. Some groups called for "dictator" Ortega and his wife to step down, yelling "Out! Out!" Ortega, a 72-year-old former Sandinista guerrilla leader who has ruled Nicaragua for 22 of the past 39 years, has been taken aback by the demonstrations against him, the biggest in his last 11-year stretch in power. He has canceled the pension reforms and called for dialogue, and Murillo has suggested arrested protesters could be released. But his security forces have not been pulled back, and -- though Managua appeared relatively calm early Tuesday -- widespread anti-government sentiment persisted. Even Nicaragua"s business sector, whose support had shored up Ortega over the past decade, has abandoned him over the violence. A pro-government rally was being organized for Thursday to show that the president still enjoyed backing from part of the population. Mass street protests are rare in Nicaragua, where the army maintains a very tight grip on public order. But dissatisfaction has been bubbling over in recent months. Frustrations have been voiced over corruption, the distant and autocratic style of Ortega and Murillo, limited options to change the country"s politics in elections, and the president"s control over the Congress, the courts and the electoral authority. In rural areas, anger also stemmed from a stalled plan by Ortega to have a Chinese company carve a $50 billion canal across Nicaragua to rival Panama"s lucrative Pacific-to-Atlantic shipping canal. If the project went ahead, it would displace thousands of rural dwellers and indigenous communities, while dealing a negative impact on the environment. "People are demanding democracy, freedom, free elections, a transparent government, the separation of powers, rule of law. The people want freedom," former Nicaraguan foreign minister Norman Caldera told AFP. "If the government doesn"t yield, it"s going to be very difficult to stop this (the protests)," he said, asserting that the "big majority" of the population was showing its frustration with Ortega. "The repressive apparatus is not able to halt protests on this scale," Caldera said. Though Ortega has held out the promise of talks with opponents, the lack of any identifiable leader in the protest movement could make dialogue there difficult. Under his watch, Nicaragua has avoided the rampant crime seen in northern Central American countries where gangs are rife. It has also put in solid economic growth, yet it remains one of the poorest nations in Latin America. The sudden upsurge in the streets puts Ortega at a crossroads: to tough it out, or to bow to the demands for democracy that have become too loud to ignore.