Workers at a fabrication yard, which was brought back into use just six months ago, have been told they will not have their contracts renewed.
Arnish in Lewis had been mothballed for about a year when it was reopened in March to manufacture parts for an offshore wind farm.
The contract was expected to create work for more than 80 people. It is understood 60 are employed at the yard.
Unite Scotland and the GMB said new contracts needed to be secured.
The work is expected to finish by the end of the year.
The unions said the news had come as a “major blow” to the workforce.
The Scottish government said it would provide support for any staff affected at the BiFab yard.
BiFab, which also has yards in Methil and Burntisland in Fife, has previously received help from the government to avoid the threat of administration.
It was reported in July that eight jackets for turbines would be built in Fife, which is a small part of the total order. However, three months on, there has been no confirmation from the principal contractor about allocation of the sub-contracted fabrication work.
A spokeswoman for the Scottish government said: “Some contracts are nearing completion, but by working with the company to secure new business, we hope to provide the best means of creating jobs in the longer term for both the Fife and Isle of Lewis communities.
“We will provide support for any staff affected by redundancy through our Partnership Action for Continuing Employment initiative.”
Arnish was brought back into use earlier this year to make piles to support wind turbines for the Moray East scheme in the Moray Firth.