Nepal's Prime Minister Sher Bahadur Deuba says he has formed a coalition government aimed at ending Nepal's long-running political deadlock.
Prime Minister Deuba - no guarantee the crisis will end
Pressure has been building for a broad-based government to resolve Nepal's Maoist rebellion and clear the way for parliamentary elections.
Earlier on Monday 12 policemen and a civilian were killed by the rebels, the authorities say.
More than 9,000 people have been killed in eight years of fighting.
The BBC's Sushil Sharma in Kathmandu says there is no indication yet that the political crisis will end, despite the prime minister's new government.
Mr Deuba was sacked two years ago by King Gyanendra who was unhappy with his handling of the Maoist insurgency.
But the king's decision to assume full executive powers outraged opposition parties.
He subsequently appointed two prime ministers. But that failed to satisfy the opposition which launched a series of strikes and demonstrations against him.
The king re-appointed Mr Deuba last month. The Maoists denounced the move, saying it would "do nothing but intensify the civil war".
The four parties in the new government are:
- The United Marxist Leninist (UML) - Nepal's largest left-wing party
- The right-wing Rastriya Prajatantra Party
- A regional grouping, the Nepal Sadbhavana party
- Mr Deuba's own Nepali Congress-Democratic party
Two nominees of the king are also in the government.
The coalition does not include one of the country's biggest parties, the Nepali Congress.
The prime minister will also keep control of the crucial defence and foreign ministries.
Our correspondent says a number of opposition parties have vowed to continue their protests as they still refuse to recognise the government.
Kidnap rescue attempt
Monday's rebel attack that left 13 people dead took place in the south of the country, police say.
The rebels are fighting for a communist state
A police spokesman said a police jeep was attacked during an operation to rescue a businessman kidnapped by the rebels south of the capital, Kathmandu.
In a separate incident, two rebels were killed in a clash with the security forces near the capital, police said.
The rebels are fighting to replace the monarchy with a communist state.
Last week the prime minister told the BBC Nepali service there could be no compromise with the rebels on issues such as the constitutional monarchy and multi-party democracy.