Tata Steel is expected to announce 1,200 job losses later - in a move which could effectively bring steelmaking in Scotland to an end.
About 400 of the affected roles are thought to be at its plants in Dalzell and Clydebridge, with the remaining 800 in Scunthorpe.
First Minister Nicola Sturgeon has already pledged to establish a taskforce once Tata's plans are confirmed, in an attempt to secure a viable future for Scotland's traditional steel industry.
It is the second blow to the sector this week following yesterday's news that Caparo Industries was to enter partial administration, with 1,700 jobs at risk.
The UK-based company, owned by Labour peer Lord Paul, has plants nationwide - but most are situated in the West Midlands.
According to the TUC, one in six British steelworkers now face the prospect of losing their jobs overall, with approximately 5,200 workers in the UK threatened with redundancy.
David Cameron has promised to raise the issue of the "dumping" of cheap steel onto the market with Chinese President Xi Jinping during his four-day state visit to the UK – however, unions say this gesture is not enough to safeguard the industry.
Roy Rickhuss, general secretary of the Community steelworkers' union, said: "The Prime Minister needs to do more than 'raise' the issue.
"He needs to tell the Chinese premier what action he's going to take to stop Chinese steel damaging the future of a vital foundation industry in the UK."
Due to overcapacity in the Chinese market, the price of steel has fallen by 40% in the past year - from about £318 a tonne to £191 a tonne. The drop has meant many UK firms are no longer able to compete.
Earlier this week China bailed out one of its own state-owned commodity miners, Sinosteel, which is facing a cash crisis and is struggling to repay its debts.
Any prospect of buyers being found for Caparo's subsidiaries by administrators at PwC is bleak, given the failure to find a buyer for SSI UK's steelworks in Redcar.
The Government held a summit last week to address the future of the ailing UK steel industry.
