Tens of thousands of people have attended a pro-democracy rally in the southern Nepalese town of Janakpur.
The demonstrators demanded that the king restore democracy
They demanded that King Gyanendra give up absolute powers and restore democracy in the country.
The rally was the biggest protest against King Gyanendra since he seized direct control of Nepal last February.
The demonstration came as the defence ministry said troops had killed 10 Maoist rebels in two separate incidents in Tanahun district, west of Kathmandu.
Eyewitnesses said more than 100,000 people attended the Janakpur rally, which was addressed by top opposition leaders.
Protesters shouted anti-king slogans and carried pro-democracy placards.
The demonstration was organised by a seven-party alliance opposed to the royal takeover.
The seven-party opposition alliance accounted for more than 90% of parliament which was dissolved three years ago.
Parliamentary elections have not been held since then due to security concerns caused by the long-running Maoist insurgency that has left more than 12,000 dead over the past 10 years.
King Gyanendra has pledged to hold municipal elections next month, followed by national elections by the middle of 2007.
Political parties have vowed to boycott the polls, which they say are aimed at legitimising his coup.
National and international pressure has been mounting on King Gyanendra to reach out to the parties and restore democracy.
He seized power, promising to crush the rebels.
Violence has worsened since the Maoists abandoned a unilateral truce earlier this month, complaining the army was continuing to attack them.
Thursday's clashes occurred in the areas of Chitre and Aambote, some 50km (32 miles) south of the tourist town of Pokhara, a statement said.
There has been no word from the rebels.
The BBC's Sushil Sharma in Kathmandu says, if the deaths are confirmed, these would be the heaviest casualties suffered by the Maoists since they abandoned their ceasefire.