Completion of a major expansion of Aberdeen Harbour has been delayed.

Aberdeen Harbour Board said the “new construction schedule” for the £350m expansion at Nigg, due next year, was now based on a phased completion in 2021.

The dredging programme has met “technical challenges”.

Aberdeen Harbour Board admitted any change in the programme was “highly regrettable”.

The £350m expansion at Nigg will allow cruise ships to berth alongside the dock, eliminating the need to ferry passengers ashore by small boat.

Harbour board chief executive Michelle Handforth said: “Aberdeen South Harbour is a visionary project, and one which will serve the region for hundreds of years to come.

“It is imperative, therefore, that we create a product of the highest quality, safety and durability.

“Any change in our programme is highly regrettable, but we’re keeping our eye on the bigger picture, which is about creating a once-in-a-lifetime economic development opportunity for the region.”

She said “excellent progress” was still being made “given the complexity of the project”.

VisitAberdeenshire chief executive officer Chris Foy said: “We echo Aberdeen Harbour Board’s comment that the South Harbour development will bring long term benefits to the region.

“We remain entirely confident that the resulting uplift in cruise traffic will drive increased tourism receipts into the region for many years to come.”

In July, one of the firms involved in the expansion had warned the project could face delays.

In an application to Aberdeen City Council, Leiths – which operates the Blackhills quarry on the site – said an increase in operating hours was necessary so the project could proceed as scheduled.

Harbour developer Dragados had increased its order from the quarry, after subsea blasting and dredging efforts failed to provide the materials needed.