Aberdeen Harbour Board said in December that the Aberdeen Harbour Expansion Project (AHEP) was 70% through construction and on track for a phased opening in 2021.

The Press & Journal has reported that more than £230m has so far been spent on the new South Harbour at Nigg Bay which will allow larger vessels to dock in the city.

However, a letter to stakeholders has revealed that funding set aside for some much-heralded parts of the development is almost used up.

Aberdeen Harbour Board said its status as a trust port means it has not been able to secure government funding amid the punishing impact of Covid.

Without additional financial support, it is feared the project may have to be curtailed, with plans for green infrastructure – thought vital to the north east’s transition from oil and gas – abandoned.

In his letter, the board’s chairman Alistair Mackenzie wrote: “To date our £350m expansion project has been largely self-funded but without assistance it will no longer be possible to introduce much needed green infrastructure, such as service trenches for clean fuels and quayside electrification, or to carry out hydrogen feasibility studies.

“Such infrastructure would play a critical role in realising the north-east’s energy transition vision.

“Without financial support, we are growing increasingly concerned that realising the project’s full potential will no longer be viable.”

Mr Mackenzie said directors “remain hopeful that a solution can be found” and they would now look to the UK Government for backing.

The project was hit by delays when Spanish-owned Dragados UK withdrew from the project last June, citing the coronavirus crisis as well as “other factors” for the decision.

Harbour board chief executive Michelle Handforth insisted the wider project, due to begin a phased opening later this year, “is not in jeopardy”.

“The fully completed Aberdeen Harbour expansion project will play a crucial role in the Scottish and UK Governments’ energy transition ambitions for the north-east,” she told the P&J.

“Unfortunately, as a trust port, we have not been able to access any of the current Covid-19 financial support schemes. Along with many other businesses the pandemic has negatively impacted our revenue.

“I must stress that while the project is not in jeopardy overall, we remain concerned that without green infrastructure development support we will not be able to fully realise the expansion project’s green port potential.”

Last month, Aberdeen Harbour Board awarded two new contracts for the construction of the South Breakwater and Crown Wall, with a total value of £60 million.