A seven-to-one majority of ESB workers have voted in favour of striking in the latest twist in a long-standing row over a deficit in the State-owned company’s pension plan.

The company’s group of unions says that there is a €1.7 billion shortfall in the staff retirement fund, although the ESB itself disputes this, and says it has already agreed a plan with regulators that will plug the gap.

Earlier, the group of unions confirmed that members voted by 87.5 per cent to 12.5 per cent in favour of industrial action, including strike, in a ballot of all five organisations that make up of the group.

The union’s claim that the company is refusing to recognise the pension pot’s shortfall, which they argue would leave workers with just 4 per cent of their benefits should it be wound up.

In a statement, the group said that the ESB’s actions had given rise to an industrial dispute.

The ESB responded by saying that it has established procedures to address industrial relations issues, and pointed out that it has invited the unions to talks with the company.

“ESB is disappointed at the outcome of a ballot today by the group of unions for industrial action,” it said.

“We acknowledge the potentially serious impact of this situation for customers and we will continue to work to resolve the issues directly with the group of unions through the established procedures.”