New energy work that began last year in Norwegian territorial waters led to an increase in emissions of carbon dioxide, a greenhouse gas, the government said.

The Norwegian Petroleum Directorate, the country's energy regulator, said the petroleum sector generated 3 percent more carbon dioxide last year than it did in 2014.

"The primary cause of the increase is start-up difficulties on the Knarr field and start-up of the Valemon and Edvard Grieg fields, which started producing in 2015," the NPD sadi in a statement. "Total CO2 emissions from producing fields that were operational before 2015 are on the same level as in 2014."

NPD said emissions are generated by the consumption of fuels on operational facilities and through the flaring of natural gas from offshore installations.

Edvard Grieg in particular was described as a transformational project in terms of oil and gas reserves when it was brought into production in November by operator Lundin Petroleum. The company discovered the field in 2007 and estimates it holds about 187 million barrels of oil equivalents, most of which exists as oil.

Lundin in early May made commitments to a low-carbon footprint. Statoil, which holds a minority share in Lundin, set a path last year toward investing up to $200 million in renewable energy by buying into startups targeting opportunities in wind power, energy storage, smart grids and other energy-related technology. The company in 2015 joined nine of the world's largest oil and gas companies in pledging to play a constructive role in reducing the intensity of global greenhouse gas emissions.

The NPD said the emissions of total volatile oil compounds were down 6 percent and methane emissions were down 8 percent from 2014.