About 450 Scottish coal industry jobs are at risk as an employer struggles against financial difficulties.
Scottish Resources Group (SRG), which owns Scottish Coal, said competition from overseas and the impact of cheap imports have put global pricing trends at "record low levels".
The company is understood to be downsizing to two locations, with its mines at St Ninian's in Fife, Mainshill in South Lanarkshire, and Binston Hill and Dalfond, both East Ayrshire, said to be "working to a close" this year.
A spokesman for SRG said the mines are not strictly closing forever, but they are being put on hold pending economic investment.
The two locations that will continue working as normal are at Broken Cross in South Lanarkshire, and Dunston Hill, East Ayrshire.
Scottish Coal currently employs 758 people, with 300 of those jobs said to be safe.
A spokesman for SRG said: "Scottish Resources Group has announced that the company is entering into formal consultation with its workforce about reducing numbers employed in the business. A number of mines are due to reach their planned limits of production this year. While a number of new sites have either been given planning permission or are currently awaiting a decision, they will be not commenced immediately. As a result, there will be a temporary reduction in productive capacity until the new sites are commercially viable.
"Coal still consistently provides between 40% and 50% of the UK's electricity needs and demand remains high. However, Scottish mined coal is priced in relation to global pricing trends which have been at record low levels. This is mainly due to a massive expansion of 'fracked' shale gas in America, which has displaced their coal on to the international market.
"We do, however, expect prices to continue to rise which will allow companies like SRG to re-establish former levels of production. And despite current challenges, the long-term future for UK coal production looks very positive."
He added: "SRG is currently in discussions with all its stakeholders, its employees, the Scottish Government and the councils where the operations take place and would like to express its gratitude for all the assistance being given."