The contractor fears funding for schemes like HS2 and Hinkley Point could be under threat when the UK leaves the EU.

The Infrastructure 2050 report warns that the UK will lose “billions of pounds in infrastructure funding” when it is forced to give up its stake in the European Investment Bank.

Balfour wants to see the shortfall made up by attracting more private investment and an increase in Government borrowing to fund projects.

The report states: “Now is an ideal time for government to borrow money in order to finance infrastructure projects.

“This is far from being an irresponsible course of action as some maintain.”

The report also warns about the dangers of skills shortages with wage rates for skilled workers in sectors like rail expected to rise by up to 40% over the next five years.

It states:  “The free movement of labour has allowed us to find the skilled staff we cannot currently source in the UK.

“Given the number of major infrastructure projects in the pipeline, uncertainty around the free movement of labour could cause the industry recruitment and staffing difficulties and may increase costs where demand for labour outstrips supply, with the subsequent risk of project delays.

“This will be particularly relevant for mega projects such as HS2 and the nuclear new build programme.

“In our view, this requires an early and integrated policy response to both retain the skills of those who have migrated here and to ensure that the UK remains an attractive place for talented people to move to.”