Offshore workers are to be balloted for industrial action in a protracted dispute over pay and conditions.
Members of Unite and the GMB will vote in the coming weeks on whether to launch action after talks with the Offshore Contractors Association (OCA) broke down on Wednesday.
The move comes after union members voted last month to reject a new pay offer from North Sea employers.
OCA said it was "extremely disappointed" at the news.
In a statement, Unite said it would press ahead with preparations for official industrial action ballots, following the failure of talks which involved the conciliation service Acas.
Unite regional officer Tommy Campbell said: "Unite members gave a significant mandate to hold a ballot for strike action in this dispute with the OCA employers.
"Offshore workers are gearing up to campaign for a yes vote. It is time for all union members to stand up now, and fight back for better terms and conditions."
OCA chief executive Paul Atkinson said: "We are extremely disappointed that the trade unions appear unwilling to engage on the issues which are so important to their members.
"Our priority has always been to find ways of avoiding any disruption.
"We approached our meeting today as a constructive opportunity to take the next step in bringing this dispute to a resolution.
"We believe that the OCA has acted as a fair negotiator throughout this process and that our approach balances the needs of employees with the requirements of business."
He added: "Industrial action will only serve to make investment in the North Sea less attractive and jeopardise the long-term future of the industry.
"We remain firmly committed to doing all we can to find a lasting solution to this dispute."