The operator of the Grangemouth refinery recorded a 10-fold increase in profits last year.
Petroineos Manufacturing Scotland Limited’s newly filed accounts show the firm’s pre-tax profits rose from £2.5 million to £25.3m for the year ending December 31.
Sales grew from £250.7m to £286.7m last year.
In his strategic report, refinery manager Russell Mann said higher than anticipated margins and good availability of services led to the stellar year.
However, he warned of “challenging” market conditions.
He said: “The longer-term outlook for European refining remains challenging in the current economic climate.
“The directors believe the steps that have already been taken to reduce overheads have paved the way to restoring sustained profitability and improving cash flow in the long term.
“Client loyalty has been retained in difficult conditions, with continued expansion of the wholesale business.
“There is every reason to believe that, as growth continues, the company can build on the foundations established.
“The company, in the meantime, continues its policy of continuous development, both in terms of its product range and its market reach with a significant volume of road transport fuels now exported to the Northern Ireland market via the Finnart Ocean Terminal.”
Safety performance during 2017 was in line with historical average, with one serous incident involving a pump fire. Two improvement notices from the Health and Safety Executive were resolved.
Staff numbers grew by 41 employees during the year — 334 classed as operations, 139 by maintenance and 61 in support services.