Journalists and bystanders were beaten with truncheons or prodded with electric batons, seemingly at random, during the clashes.
At least 10 people were injured in clashes last Monday, as opposition member Mu Sochua staged a demonstration to try to enter the park in protest of a government ban on public assembly.
A senior UN rights official on Tuesday urged Cambodia to conduct a proper investigation into violence that has taken place since the July 2013 elections, as well as to speed up land titles for indigenous groups.
Flavia Pansieri, Deputy High Commissioner for Human Rights, will visit prisons that benefit from UN human rights assistance, along with resettlement sites for families evicted from development projects.
Protesters on Monday brought with them tents, pillows, and cooking equipment, with plans to stay overnight on the grounds in front of City Hall.
Activists and police clashed outside the Phnom Penh Municipal Court building on Friday, where 23 labor activists were brought for trial following their arrests in January.
Some 100 supporters clashed with an equal number of riot police outside the court, where a number of protesters were injured.
Supporters gathered outside Prey Sar prison on Wednesday, holding a Buddhist celebration to pray for the detainees’ release.
The draft law, which was leaked to the public recently, imposes major fines and jail time for vague offenses and has many online users concerned.
Rong Chhun, head of the Cambodian Confederation of Unions, is making a trip through the US, seeking support to help free 21 labor activists who have been in jail since deadly crackdowns on demonstrations in January.
Rong Chhun told VOA Khmer Tuesday the US is a major market for garments produced in Cambodia and a major donor to Cambodia.
Seven families in at the site, in Boeung Kak 1 commune, Tuol Kork district, are embroiled in a land dispute with the Khun Sear Import & Export Company.