Engineering work for the first phase of HS2 is already £10.6 million over budget.

This is according to Building magazine after it analysed figures from the Department for Transport (DfT), concluding civil and structural design services were above the estimated total of £58.7 million.

The findings have not been met positively by the scheme's opposition, with the costs being a crucial factor.

Richard Houghton from HS2 Action Alliance said: "Consultants are always happy to let budgets grow. But the fact that all the contracts are over budget points to unprofessional and slack management from the DfT and HS2 Ltd."

Capita, in cooperation with Ineco JV, was the most over-budget, with costs going up 42 per cent to £4.6 million for its work on the north section. This was followed by Arup, going up 27 per cent to £14.6 million in Birmingham and 17 per cent to £11.2 million at Euston station.

Mott MacDonald also put its price up by nine per cent (£14.4 million) for the London metropolitan area, while Atkins had the smallest change, adding 0.4 per cent (£13.4 million) for the south section.