KATHMANDU - Nepal's army and police have been placed on high alert, a government minister said Tuesday, after the opposition Maoist party announced plans to blockade the capital and shut down the main airport.

Finance Minister Surendra Pandey said the Maoists' plans were in breach of the 2006 peace agreement signed by the former guerrillas, who have held regular protests in Nepal since their government fell in May.

"The government has placed all the security agencies on high alert in view of the protests," said Pandey.

"The Maoists have violated the spirit of the comprehensive peace accord by announcing plans to blockade the Kathmandu Valley and shut down the airport. This is not a democratic way to press for their demands."

The Maoists, who fought a 10-year civil war against the state before winning landmark elections in 2008, last week announced a fortnight of nationwide protests aimed at destabilizing the new coalition government.

They have vowed to bring Kathmandu to a standstill on November 10 by shutting the country's only international airport during the peak tourist season and blocking all roads into the capital.

They are calling for the president to apologise for blocking Maoist leader Pushpa Kamal Dahal's attempt to sack the head of the army, a move they say was unconstitutional.

Maoist spokesman Dinanath Sharma denied the protests were in breach of the peace agreement, which prohibits the "spread of social disharmony in any manner, including acts of incitement and instigation."

"We have the right to organize peaceful protests. We have been forced into this because the government is not listening to our demands," he said.