Four people have been killed and seven others injured after three explosions in separate areas of Kathmandu, a police spokesman says.
"One bomb went off in Ghattekulo area and another one exploded in Sukedhara," said the spokesman, Bishwa Raj Pokharel.
"The wounded are being treated in two hospitals in Kathmandu."
"We are investigating all incidents and have stepped up the security."
Mr Pokharel said that seven people have been arrested so far.
There was no immediate claim of responsibility but police said they suspect the involvement of a Maoist splinter group whose pamphlets were found in a house where one of the explosions took place.
A powerful blast inside a shop killed three people and injured four, while the explosion at a home about four kilometres away left one dead and another injured.
Two more were injured when an explosive they were carrying on a motorcycle in the outskirts of Kathmandu exploded.
Security personnel also defused explosives in other areas.
The incidents come on the eve of a nationwide strike called the same Maoist splinter group, protesting the death of their cadre in a police encounter over a week ago.
Nepal has enjoyed a relatively peaceful environment since the end of a decade-long civil war which concluded with a peace deal struck in 2006.
But some former guerrillas, have broken away, accusing its leaders of betraying their original revolutionary ideals.
In February, the group was implicated in an explosion that killed one person outside the office of a telecom company Ncell, part of Malaysia-based Axiata Group Berhad.
The government outlawed the group following the incident, banning their activities.
