American police have arrested more than a dozen people attending anti-corporatism protests in the country, a report says. Police detained eight Occupy protesters at the Democratic Party headquarters in the city of Des Moines in Iowa, while another six demonstrators were captured in San Antonio in Texas on Monday. Earlier this week, Occupy Des Moines took over President Barack Obama's election campaign headquarters and refused to leave. The protesters are demanding the US president veto the National Defense Authorization Act, which gives authorities the power to detain terror suspects without trial. The New York-based Human Rights Watch has also criticized the measure and lashed out at Obama for supporting it. Commenting on the bill, US Republican presidential hopeful Ron Paul has accused Obama of pushing for institutionalization of martial law in the country, thus jeopardizing the freedoms of US citizens. There have been 5,425 arrests during Occupy protests in 94 cities across the US up to December 12, according to St. Pete for Peace, an Occupy-affiliated group from St. Petersburg, Florida. Over the past few weeks, police have broken up Occupy encampments in cities and towns across the US, harshly attacking and arresting dozens of protesters. The Occupy Wall Street movement began when a group of demonstrators gathered in New York's financial district on September 17 to protest against the unjust distribution of wealth in the country and the excessive influence of big corporations on US policies. Despite the police crackdown and the mass arrests, the Occupy movement has now spread to many major US cities.