Hugo Chavez's government has blamed droughts for power rationing
Venezuela has imposed sweeping power cuts on industry and businesses in order to save its limited energy resources and avoid mass blackouts.
The government said the cuts were because of falling water levels at the Guri Hydroelectric dam, which supplies much of the country's power.
Energy Minister Angel Rodriguez said that without cuts, the dam could stop feeding the power grid early next year.
A drought in the region has caused water levels to drop dramatically.
Shopping centres have to turn off their lights by 2100 as part of the widespread rationing, while casinos and bingo halls have to turn theirs off by midnight.
Billboards also have to use energy-efficient light bulbs.
Businesses that do not comply with the new measures will be forced to close for one day, or three days for repeat offenders.
The government also told businesses to draw up plans to cut energy use by 20%.