The company said its net profit between January and March stood at 158 million dinars ($1.49 million), down from 3.7 billion dinars in the first quarter of 2018.

NIS earnings before interest, tax, depreciation and amortisation (EBITDA) stood at 6.3 billion dinars, down from 8.9 billion dinars a year earlier.

"Financial results ... have been influenced by lower average crude oil prices compared to the first quarter of 2018, capital overhaul of the oil refinery in Pancevo and higher amortisation," it said.

In its Pancevo refinery, 13 kilometres north of Belgrade, the company produced 321,000 tonnes of oil and gas equivalent in the period, it said. Its annual average output is 1.7 million tonnes of oil and gas equivalent.

In March NIS started building a 200 megawatt (MW) gas-fired cogeneration plant which will be built by China's Shanghai Electric Group at an estimated cost of 180 million euros.

The total value of the company's investments in exploration, production and capacity modernisation in the first quarter stood at 8.3 billion dinars, or 6 percent more than in the first quarter of 2018, it said.

One of the biggest contributors to Serbia's budget, NIS operates two refineries, plus fields in Serbia, Angola and Bosnia.

NIS shares rose 0.27 percent to 747 dinars on Thursday.

Gazprom Neft owns 56.15 percent of NIS, while the Serbian government holds a 29.88 percent stake and small shareholders the rest.