Unite said its members had been treated "disgracefully" after they were escorted from the sites yesterday (21 June) by security guards after being informed of the closures and told that June's wages would not be paid.
According to Unite regional officer Kathy Brooks, BemroseBooth chief executive Jean-Paul Ansel blamed Marks & Spencer's decision to stop dealing with the company, together with major problems related to a promotional products contract for the closures.
BemroseBooth filed a notice of intent to appoint an administrator at the High Court of Justice last week (16 June), suggesting it could be on the verge of administration.
David Stephenson, senior manager at David Rubin & Partners, confirmed that BemroseBooth was not yet in administration and that the insolvency firm had not been appointed as administrator.
He said: "The company is in financial difficulty and it has filed a notice of intention to appoint an administrator.
"It is likely that it will be going into administration in the not too distant future."
Stephenson added that, by filing a notice of intent, the company would be protected while it is being marketed.
He confirmed that BemroseBooth's Riverside site had shut, following the loss of a major contract, and that its head office, also in Derby, had closed with the total loss of 160 staff at the two sites.
The company's Hull and Teeside sites are trading as normal, as were the other parts of the business, which are being actively marketed by Edward Symmons.
Stephenson said: "We are confident that we'll find a buyer but it does depend on the level of the offer."
Unite's Brooks claimed that the company had failed to consult meaningfully with the union, if at all and that Unite was now taking legal advice on its options.
"The union is shocked and appalled at the manner in which the company has chosen to deal with this issue," she added.
"It is the union's view that the company has demonstrated a blatant disregard of the law that places a duty on an employer to engage in meaningful consultation in good time."
BemroseBooth's Ansel told PrintWeek that the company was currently being restructured to make it profitable.
However, he declined to comment on the formation of new company, Bemrosebooth Systems, which was created on 8 June 2010 and which lists Ansel, and Leonard Levie, of BemroseBooth's US-based owner AIAC, as directors.