The rebels will hold 25 per cent of the seats in the temporary parliament.

"The cabinet meeting Sunday approved the finalised interim constitution due to be presented before parliament tomorrow," Deputy Prime Minister Amik Sherchan told AFP.

"The Maoists will enter parliament for the first time and the house session will pass the interim constitution on the same day after discussions," he added.

The former rebels fought a violent "people's war" for a decade in the impoverished Himalayan nation to install a communist republic, but have now agreed to join mainstream politics.

The temporary constitution has provisions which formally remove the king's status as head of state, with his executive powers passing to the prime minister.

The interim constitution grants the former rebels 83 seats in a new 330-seat parliament. Among their delegates are representatives of marginalised groups never present in parliament in Nepal before.

The Maoists are expected to join the cabinet within a couple of weeks, but negotiations are still to take place on which posts they will hold.

Once former foes, the rebels and government have observed a ceasefire for nearly nine months, and the rebels have agreed to place their weapons and army under UN monitoring.

The Maoists are expected to start placing their weapons in containers under UN supervision Monday, but as part of the peace deal the rebels will retainkeys to the locked-up weapons.

The parliament due to be sworn in Monday will oversee elections to a body that will draft a new version of Nepal's constitution, and address the future of the monarchy, a long-held rebel demand.

The Maoists are keen to see Nepal become a republic but some other parties want a ceremonial monarchy.