KATHMANDU -- A general strike ordered by Maoist rebels shut down Nepal on Tuesday, highlighting a pervasive fear of the guerrilla group which is fighting to topple the monarchy, Reuters reported.

Even in the normally bustling capital Kathmandu, streets were empty of traffic and those daring to leave their homes had to walk. Businesses and schools were closed and shops shuttered at the start of the strike the rebels say should last five days.

Police said there were two small bomb explosions in Kathmandu on Monday night, but there no signs of trouble early on Tuesday.

Troops, carrying assault rifles and wearing camouflage, guarded the streets and occasionally checked passers-by.

But despite the heavy security presence, Kathmandu residents said they feared retribution later if they defied the Maoists -- who operate mostly from the countryside but also run a shadowy network of sympathizers and activists in cities.

"If I open my shop Today, they would take note of it and attack me some other day. How can I risk it?," Said Ram Bahadur Chhetri, who owns a small greeting card shop in Kathmandu.

A local taxi driver who had dared to work had covered up his number plate "to hide it from the Maoists", he said. "They will note down the number of my taxi and assault me some other day."

Residents in other major cities told Reuters by telephone they had also mainly closed down for the strike.

A local journalist in Nepalgunj, a southwestern town on the Indian border, said police there had forced some shops to open to try to break the strike, but no one was on the streets.

Maoist rebels, battling to replace the Himalayan kingdom's constitutional monarchy with a one-party communist state, launched a wave of intimidatory attacks ahead of the strike.

These included bomb blasts in Kathmandu, one just three km (two miles) from the prime minister's heavily guarded official residential compound, on Sunday.

More than 3,500 people have died in the six-year rebellion, inspired by late Chinese leader Mao Zedong's campaign to give power to peasants and end the privileges of the urban elite.

On the eve of the strike, Kathmandu shopkeepers said they would close down rather than risk the wrath of the Maoists.

"The Maoists might firebomb us," said one shopkeeper selling shawls and rugs just a short distance from a major tourist hotel. "If they don't bomb, they might chop me."

The United States on Monday issued a warning to its citizens on the increased dangers of travelling to Nepal.

"While no tourists have been attacked to date, the dangers of Americans being caught in the wrong place at the wrong time have increased in the periods leading up to bandhs (strikes)," it said.

Nepal is still reeling from the massacre of popular king Birendra and several other members of the royal family by crown prince Dipendra last June.

It has been living under a state of emergency, which gave the police widespread powers of search and detention, since late last year when Maoists broke a cease fire and launched attacks on police and army targets across the country.