Another activist was arrested in Phnom Penh on Thursday as the U.N., international rights groups and dozens of local civil society organizations condemned the government�s �campaign of fear and repression� against human rights defenders.

Police arrested Muong Sopheak on Sothearos Blvd. in Chamkarmorn district�s Tonle Bassac commune around 3 p.m. by court order for incitement to disturb social security, municipal police spokesperson San Sokseyha said on Friday.

His brother, Muong Sony, said Sopheak had been taken by authorities from outside the minor Khmer Will Party�s headquarters. Sopheak and Sony both belong to the Khmer Student Intelligent League Association, two other members of which were arrested last weekend in relation to protests in support of jailed unionist Rong Chhun.

Sopheak�s arrest marks at least 10 activists arrested over the past month amid a series of small street protests, most in support of Chhun. At least four of those detained were members of youth activist group Khmer Thavrak.

Chhun was arrested in late July after alleging that Cambodia was losing territory to Vietnam along their shared border, a controversial and ethnically charged issue.

In a statement on Friday, the U.N.�s human rights office said it had documented the arrests of 24 human rights defenders since Chhun�s arrest, 12 of whom remained in detention.

Several activists also reported being followed and receiving threatening phone calls, including death threats, it said. �Numerous human rights defenders are currently in hiding for fear of being arrested.�

�The current situation marks a deepening of the Government�s intolerance to dissent and repression of the rights to freedom of expression, peaceful assembly and association,� it said, calling on the government to release the arrested activists and end the intimidation against civil society actors.

Human Rights Watch deputy Asia director Phil Robertson also called for the activists� release in a statement on Friday, and urged Prime Minister Hun Sen to �end the de facto ban on critical protests in Phnom Penh.� On Thursday, Amnesty International condemned the arrests as �a shocking, all-out assault on Cambodia�s youth.�

Thirty-nine civil society groups signed a similar statement earlier this week. �We urge the government to end its campaign of fear and repression against peaceful youth and environmental human rights defenders,� they said on Wednesday.

The government�s permanent mission in Geneva this week responded to related criticism from U.N. envoy Rhona Smith.

�Cambodia cherishes freedom of expression, association and peaceful assembly in line with the law, and is deeply conscious that plurality of voices, including the critical one, matters in the development of the country,� it said in a statement, according to state media outlet Agence Kampuchea Presse. �However, article 31 of the Constitution of Cambodia underscores that exercise of personal rights and freedom by any individual shall not adversely affect rights and freedom of others. The exercise of such rights and freedom shall be in accordance with the law.�