'Soul cry. This is black smog over the city. Those who do not go to the suburbs cannot imagine the contrast.' Picture: Svetlana Nazarova

These startling pictures show the city in what residents call 'Black Sky Mode', prompting an online petition to mayor Edkham Akbulatov and regional governor Viktor Tolokonsky demanding an improvement in the ecology.

Blue skies and bright sunshine are entirely blotted out by the 'veil of pollution' hanging over the city. Pictures posted by local people show a 'dangerous' environmental situation, they claim.

Svetlana Nazarova captioned a picture in her Instagram: 'Soul cry. This is black smog over the city. Those who do not go to the suburbs cannot imagine the contrast.

'The city is covered by #blackskies, it is rather a #blackhole - and it lasts since the beginning of the year.' Pictures: Daria Tarasenko, Alexey Gudkin, Inna Maklakova, Ksenia Staranchukova

'In the woods today is the brightest sun and blue sky. Trees, shrubs and snow shining in the sun. And in the city is a grey veil, no air to breathe. I began to hate Krasnoyarsk. It is dangerous to live here.'

Daria Tarasenko posted: 'It seems that they [officials] gave up on the city's ecology. If my children want to leave, I will understand them.'

Olga Lomovtseva warned: 'The city is covered by #blackskies, it is rather a #blackhole - and it lasts since the beginning of the year. Nothing to breathe!'

Residents constantly feel a 'chemical smell' and the fears is expressed that officials do not disclose the sources of the pollution. Pictures: Olga Lomovtseva, Katya Churuksaeva, Dmitry Egorov, Viktor Belogurov

Officials have failed to explain the sources of pollution, according to some locals. The petition has been signed by more than 12,000 people in the industrial city. Residents constantly feel a 'chemical smell' and the fears is expressed that officials do not disclose the sources of the pollution.

They expressed the concerns that the main sources are local factories, but that no one wants to impose limits on the fumes they pump into the atmosphere, or force the use of new filters. One suspected source of the problem is a landfill where sawdust has been burning for five months at Yenisei Pulp and Paper Mill.

One suspected source of the problem is a landfill where sawdust has been burning for five months at Yenisei Pulp and Paper Mill. Pictures: Alexander Chernykh

The governor insisted that urgent action is underway to install 'new higher-quality equipment' leading to better pollution control by factories. 'These programmes will be controlled strictly, and if a company does not perform activities they would face sanctions stronger than envisaged by the environmental legislation,' he said. 'We have the political will, and I openly say this to all businesses.'

But some pollution was caused by stoves and fires necessary for heating private houses in the cold weather, he said. 'I cannot appeal to people and say, 'Listen, stop use the stove, because of a lot of emissions'. It will pass. When the cold weather ends, everything will be restored.'

Lately, Krasnoyarsk - a historic city founded in 1628 with a population of 1.04 million - has had typical winter temperatures of below minus 20C.