Oil and gas exploration firm Tullow Oil reported a pre-tax loss of $1.3 billion (£895 million) as low oil prices took their toll.
It was the company’s second successive year in the red, with the 2014 pre-tax loss $2bn (£1.4bn). Revenues in 2015 fell 27% to $1.6bn (£1.1bn).
Tullow warned that this year it could fail to comply with its financial covenants agreements made with lenders to maintain a stable financial position.
Oil prices have slumped by 70% since the middle of 2014, with many of the oil majors cutting back investment on exploration and production.
More than 5,000 jobs have gone in the North Sea oil industry.
Tullow could cut annual capital expenditure to $300m next year, down from $1.1bn planned for this year, if market conditions do not improve.
It has reduced its headcount by 37% and is on track to deliver cash savings of around $500m over three years.
Tullow’s results followed a report by industry body Oil & Gas UK which found companies are increasingly pessimistic about their business prospects.
The Q4 2015 Business Sentiment Index surveyed representatives from both operator and contractor companies.
Oonagh Werngren, Oil & Gas UK’s operations director, said: “The deteriorating market conditions and the scarcity of new business opportunities continue to be major concerns for the industry.
“Many companies remain deeply apprehensive about the future, with two thirds reporting activity down further in the fourth quarter of 2015 compared to the previous quarter.”
Over half of all respondents reported a reduction in headcount and two-thirds reported falling revenues.