"A mutual ceasefire between the Communist Party of Nepal (Maoist) and the government of King Gyanendra, and steps towards lasting peace, are crucial to bring to an end a period of grave violations of human rights and international humanitarian law by both the Maoists and the State", Arbour said in a statement.

The UN High Commissioner for Human Rights joined calls for Maoist rebels to extend a unilateral ceasefire, which is due to end this week and urged the Nepalese government to join it.

"I am seriously concerned about the very real possibility that full-scale armed conflict could resume," she added.

Last week, the Maoists and the opposition parties agreed on an alliance to attempt to restore democracy to the Himalayan kingdom.

Local officials in the Nepalese capital have banned protests by the communist party planned for December 2, state-run media reported on Wednesday.

The Kathmandu district administration office has barred public meetings, processions, sit-ins and strikes in four areas of the city in an effort to head off the planned protests, the Gorkhaptra newspaper reported.

On Tuesday, the Nepal Communist Party-United Marxist and Leninist (NCP-ML) and six other opposition parties announced they would begin a month-long series of protests starting Friday when King Gyanendra returns from an overseas tour.

The NCP-ML Wednesday rejected the ban and said it would proceed with the demonstrations.

"The programme will be held at the same venue and the party appeals to the public to participate in the programme that day," it said in a statement.

Nepal's Communist party was hopeful yesterday that tens of thousands would take to the streets to protest King Gyanendra's power grab as the monarch returns home and a rebel Maoist ceasefire ends.

King Gyanendra returns Friday after three weeks in Bangladesh and Africa, his first foreign foray since sacking the government and assuming absolute power in the Himalayan kingdom on February 1.

"The state is trying to arrest those fighting for democracy," NCP-UML spokesman Pradip Nepal told AFP Thursday. "This is state terrorism against those trying to hold peaceful demonstrations."

"We expect more than 60,000 people to participate in the demonstration on Friday," he said.

Human rights activist Subodh Pyakural warned of grave dangers as the three-month Maoist guerrilla ceasfire comes to an end also on Friday.

"Now the king has to compromise or be ready for a civil war in the country," he said.