KATHMANDU - A recent rise in violence by political parties and their affiliates in Nepal could threaten a three-year-old peace process, the UN human rights representative in the country has warned.

The Himalayan nation has been hit by a series of at times violent protests since the Maoist-led government fell in May after just eight months, following a failed bid to sack the head of the army.

The UN Office of the High Commissioner for Human Rights in Nepal said it was "concerned that the growing number of acts of violence by political parties and affiliated groups, and subsequent threats of retaliation, could threaten the peace process."

"The Office calls on the leaders of political parties and their affiliated bodies to ensure that their cadres respect the rights of other political parties to peacefully carry out their lawful activities," it said in a statement issued late Thursday.

The Maoists, who fought a decade-long civil war with the army before signing a peace agreement in 2006, have called a series of nationwide strikes in recent weeks, demanding the closure of schools and offices.

They have also clashed with supporters of the centre-left UML, which leads the coalition of parties that replaced them in government.