Police have arrested dozens of activists taking part in a strike aimed at crippling Nepal's capital Kathmandu.
Opposition parties called the strike to protest at the government's decision to draw up a draft constitution by next week without their agreement.
The one-day strike hit factories, schools, colleges, markets and public transport.
Police said they detained activists who were vandalising vehicles which were still running and defying the strike.
"In two cases, protesters broke the windows of moving vehicles. In another case cadres threw stones at a taxi, injuring a passenger inside," a police spokesman told AFP news agency.
No constitution yet
The opposition alliance, made up of 30 parties, is headed by former Maoist rebels, who waged a decade-long insurgency that ended in 2006 with a peace deal.
Since the civil war, Nepal's politicians have yet to draw up a new constitution, with parties in parliament, known as the Constituent Assembly, disagreeing over how to divide the country into states.
The Maoists, have pushed for new states to be created along ethnic lines to recognise and help minorities, but others have said that is too divisive.
The Constituent Assembly is aiming to get a draft constitution ready by 22 January.
When Prime Minister Sushil Koirala was elected in February 2014, he had promised to see this done within a year of his appointment.
Opposition alliance spokesman Prem Bahadur Singh was quoted by AFP as saying: "We called the strike to oppose ruling parties' attempt to establish a new constitution by exploiting their majority numbers in the assembly.
"We will call more protests if the ruling parties neglect our demands."
AP news agency reported that another general strike has been planned for next Monday.