Fears are growing that a spill from an oilfield in northern Russia could reach the Barents Sea as frozen lumps of oil are swiftly being carried downstream on a river - although the operator's parent company, Lukoil, has said clean-up efforts are in the "final stages".
Last week's spill on the Oshskoye field in the Nenets region has already spread 300 kilometres downstream.
Oshskoye operator Lukoil-Komi estimated that 660 barrels of oil has leaked from a ruptured pipeline, 300 metres from the Kolva River.
However, it said a large amount of the oil has remained at the accident site, flowing to a nearby onshore area.
Lukoil-Komi added that booms have been deployed at seven locations along the Kolva, with oil still being collected from the river surface.
However, according to local environmental group Save Pechora Committee, residents in the village of Mutny Materik reported seeing and smelling oil last weekend.
Mutny Materik is near the Pechora River, 160 kilometres downstream from the city of Usinsk, where the Kolva river flows into another regional stream, the Usa.
About 20 kilometres from Usinsk, the Usa River drains into the Pechora, which then traverses the Komi region to the Barents Sea.
Authorities have declared a state of emergency in Usinsk as the spill is endangering the city water supply system.
Komi Governor Vladimir Uyba visited the village of Kolva last weekend to oversee efforts to remove oil from the river. He did not give any estimates of the size of the spill.
In videos of his visit, posted by villagers, Uyba vowed to arrange an alternative water supply for residents and provide other assistance, while authorities continue the clean-up effort.
He said Lukoil-Komi was unable to detect the pipeline leak promptly because of a lack of “automatic controls”.
Lukoil-Komi is a wholly owned subsidiary of Russian privately held producer Lukoil.
Uyba said he plans to meet Lukoil chairman Vagit Alekperov in June to discuss assistance it may agree to extend to local residents, who also depend on river fishing.
Clean-up 'in final stages - Lukoil
Lukoil said in a statement on Monday afternoon that the clean-up effort is in its "final stages".
"Populated areas and business facilities, including those situated in the Arctic zone of Russia, are in no danger," it added.
"The clean-up involves over 100 employees of Lukoil and qualified contractors, over 30 pieces of machinery. They act in close cooperation with authorities."
The company added that "less than 9 cubic metres of oil-containing fluid found their way to the Kolva River".
"Containment and recovery operations started immediately. There are no deaths of biological resources caused by the accident," it said.
Lukoil added: "Drinking water supply sources are in no danger. Water supply facilities of the city of Usinsk are located on the Usa River, upstream of the Kolva River inflow. Rural populations are supplied with water from water wells located in the settlements."
Announcements have been posted in local social network groups to search for volunteers who can use their own boats to assist in collecting oil from the Kolva river.
Yamal-Nenets spill size denied
Meanwhile, another Russian oil producer, Gazprom Neft, has rejected estimates by a regional department of the Ministry of Emergency Situations that about 2500 square metres of land had been polluted by an oil and water mixture at the Karamovskoye field in the Yamal-Nenets region in West Siberia.
The ministry said about 3000 cubic metres of such a mixture escaped from an infield pipeline last week.
However, Gazprom Neft said around 850 kilograms — amounting to about six barrels — was leaked, polluting an area of 250 square metres.