In 2020, investments are expected to fall to 158.5 billion crowns according to initial forecasts, but the forecasts could be revised upwards in the months to come, it added.

"Several plans for development and operation (PDOs) are expected to be submitted to the government in both 2019 and 2020," the agency said in a statement.

"If the schedules for these plans are realised, the accumulated investment costs in 2020 from these projects will increase the investment in field development compared to the present estimate."

Norway's oil and gas investments have rebounded from a sharp fall as rising crude prices and cost cuts lift industry activity. It was SSB's fourth release of companies' forecasts for 2019 and the first for 2020.

Equinor is Norway's largest oil firm.