Reuters cited Neste Oil chief executive Matti Lievonen as saying that between 2016 and 2017, the company is planning to modify and upgrade its 206,000-barrels-per-day (bpd) Porvoo refinery and 58,000 bpd Naantali refinery.
Lievonen said: "We will lower the costs on the Naantali side and then we are increasing the complexity and products slate for more valuable products at Porvoo.
"We will modify Naantali refinery to make more feedstock for the Porvoo refinery, so we will lower the costs."
As part of the plan, Naantali will produce vacuum gasoil (VGO), which will be used for producing oil products such as diesel and aviation fuel at Porvoo refinery.
Most of the crude oil and the expensive secondary VGO feedstock of the Porvoo refinery are sourced from Russia.
The Porvoo refinery is scheduled to be closed in April for an eight-week maintenance turnaround.
Neste also operates renewable diesel refineries in Singapore and Rotterdam.
Capable of producing approximately 2 million tons of petroleum products a year, the Porvoo refinery is located in the Kilpilahti industrial area, about 30km east of Helsinki.
The Naantali refinery can produce about 3 million tons of petroleum products annually.
