Maoist activists on Tuesday blocked all roads in and out of Nepal's capital Kathmandu in the latest stage of a two-week protest against the government.

Riot police stood on guard as hundreds of activists waving Maoist flags rallied at the main entry and exit points to the capital, but an AFP reporter at the scene said the protest appeared peaceful.

Nepal's Maoist-led government fell in May after the president halted their attempt to sack the head of the army, and the party is holding a fortnight of nationwide protests against the new administration.

"We want to hold a peaceful protest to reiterate our commitment to democracy," party worker Prakash Acharya told AFP. "In a democracy, peaceful protest should be allowed."

Police inspector Angur Gharti Chhetri said hundreds of people had been left stranded by the blockade.

"Not a single private or public vehicle has passed since early morning, although they are letting ambulances, diplomatic vehicles and tourist buses operate," he told AFP.

"The protest has so far remained peaceful."

The Maoists, who fought a 10-year civil war against the state before winning landmark elections in 2008, want the president to apologise for preventing the army chief's removal - a move they say was unconstitutional.

Their protest will continue on Thursday and Friday with a blockade of government buildings in the capital.

They initially threatened to shut Kathmandu airport, but backed down under international pressure.