Armoured personnel carriers mounted with machineguns were stationed across Kathmandu, while thousands of soldiers and police in green and blue camouflage fanned out to guard almost every street, square and junction.

Police said about 200 people had been detained for violating the curfew.

Former prime minister Girija Prasad Koirala and other leading politicians were put under house arrest before dawn on Friday, hours before the rally was due to take place to press King Gyanendra to restore democracy.

The crackdown was effective and the ancient square due to host the demonstration was deserted throughout the day. Police armed with rifles and machineguns sat on temple steps or took shelter from the sun under ornate pagodas.

More than 100 politicians and student activists were also detained on Thursday and mobile phone links cut.

UN Secretary-General Kofi Annan said he was dismayed by the arrests, while the United States, the European Union, Japan and neighbour India joined in the criticism.

At Koirala's house, armed police prevented a Reuters team from entering, or meeting the former prime minister, who is spearheading a multi-party alliance against King Gyanendra. Guards said phone lines to the house had been cut.

"This is an extreme form of dictatorship by the king," Koirala's Nepali Congress party said in a statement.