Hundreds of opposition activists have been arrested across Nepal on the eve of the first anniversary of the royal coup, the opposition says.
The opposition has vowed to step up protests
An opposition spokesman said up to 1,000 people had been detained ahead of rallies planned nationwide to mark King Gyanendra's seizure of absolute power.
Dozens were held in Kathmandu during a women's rally, the spokesman said. Official figures were unavailable.
Local elections are due next week which the opposition are boycotting.
They say the vote is an attempt to legitimise the king's rule.
On the eve of the anniversary, the US renewed its appeal for the king to begin a dialogue with political parties and restore democracy in Nepal.
A State Department spokesman said such a move was crucial to stopping the Maoists, who he said posed an immediate threat to peace and prosperity.
King Gyanendra sacked his government and seized executive powers on 1 February last year, accusing officials of having failed to suppress a Maoist rebellion which has gathered pace in recent years.
He has been under pressure domestically and internationally to return the kingdom to democracy.
The king says local elections planned for 8 February will precede parliamentary elections by the middle of next year.
Observers doubt that free and fair elections can be held in Nepal, given the worsening security situation.
The Maoists have promised violence to disrupt the poll. They are blamed for killing at least one candidate, shooting and wounding another and kidnapping a third.
Many candidates have withdrawn following the rebel threats, leaving about a quarter of the more than 4,000 seats with no one standing at all.
The authorities said on Tuesday that candidates had been told to remain in police custody for their own protection ahead of the vote.