The Grimsby firm made the statement after days of speculation about a sale.
It said: "The board of Cosalt confirms that it has been approached with regards to a potential offer for its marine business.
"These discussions are not sufficiently advanced for there to be any certainty that a transaction would be concluded or as to the price and other terms upon which it would be concluded.
"A further announcement will be made as appropriate."
Last month Cosalt said it had uncovered a 4m hole in its offshore division's accounts, stemming from "a series of doubtful transactions".
It started probing its Aberdeen-based offshore division in early September, and suspended its head Calum Melville. Mr Melville and his brother Stuart, the division's operations director, have both resigned.
Cosalt said the internal review revealed "evidence of a company-owned stock and work in progress shortfall of up to 4m". It is probing deeper to further establish the extent of the losses.