A state of emergency has been declared in the northern Russian city of Usinsk after an oil spill was spotted in the Kolva river, with a regional oil producing subsidiary of Lukoil taking the blame.

Authorities in the Komi region declared the emergency after oil was discovered on the river surface on 11 May.

Usinsk is located near the mouth of the Kolva river, which flows from the oil-rich Nenets region into the Usa river, which in turn flows into a region’s major artery, the Pechora river.

Supply systems in Usinsk and other cities downstream use the Kolva river as a source of water for residents.

According to the Usinsk city administration, traces of oil were initially spotted near the Fourth bridge that stretches across the Kolva river near the city.

A further investigation upstream found oil near the First bridge, which crosses the river about 130 kilometres away from Usinsk in the Nenets region.

Authorities have ordered the installation of oil-containing booms on the river at these two locations.

Lukoil-Komi, which is the regional subsidiary of Russian privately held oil producer Lukoil, said that, following a helicopter flight along one of its pipelines in the Nenets region, it has been able to identify the source of the spill.

Lukoil-Komi uses this pipeline to transport oil from the Oshskoye field to the receiving terminal at the Kharyaga field before it is processed and pumped into a major trunkline, operated by state-controlled Transneft.

The subsidiary has not given any assessment of the size of the spill, saying on Wednesday that it is sending its oil spill response teams to the site of the accident.

Ivan Ivanov, head of local environmental non-governmental organisation, Committee to Save Pechora, told Upstream that authorities are providing “contradictory information” on where oil had been observed.

It is too early to arrange an independent expedition to investigate the impact of the spill on the river and assess its size, he said.

In October last year, authorities declared an emergency after another pipeline spill led to an unknown volume of oil reaching the Kolva river.

Lukoil-Komi was eventually identified as the owner of a ruptured pipeline that leaked oil to the river, with the company assessing the size of the spill at only a handful of barrels, arguing that the pipeline was idle.