The operator of Belfast harbour plans to spend £1.3bn over the next 25 years to take advantage of strong economic growth in Northern Ireland, in what would be one of the largest non-governmental investments in the region’s history.

The Belfast Harbour Commissioners said the money would be spent on upgrading the port, with the possibility of residential property developments that could add another £750m in investment on top.

The harbour, a non-profit trust port that occupies a central position in the city, is already pushing ahead with the first £300m of investment, including spending on new facilities for offshore wind projects. Its other projects will include quays for grain and animal trade, upgrades to the ferry terminals, expanded container shipping facilities, and power connections for docked cruise ships.

Northern Ireland’s economic growth has outpaced the rest of the UK in recent years, with hopes for further acceleration given the post-Brexit settlement that gives the nation access to the UK and EU markets.

The harbour investment plan will be contingent on the Northern Ireland assembly passing changes to legislation and government accounting that will allow the commissioners to borrow money on financial markets. Joe O’Neill, the chief executive of Belfast harbour, said he was “comfortable” that the changes would be made by the spring of 2027.

Belfast harbour is an independent statutory body, meaning it has no recourse to public funding and must make all investments out of its own funds.

O’Neill said the port also hoped to benefit from the development of the 100-mile stretch from Dublin to Belfast, the two largest cities on the island.

“If there’s accelerated economic growth then we are building ahead of the curve,” O’Neill said. “As capacity tightens at key ports on the Irish east coast, we are putting the scale of our estate to work providing the planned capacity the island needs.”

Annual Belfast port trade could rise from 24m tonnes to between 30m and 50m tonnes by 2050, according to forecasts prepared by a consultancy.

Belfast harbour is largely built on reclaimed land, where it once had a world-leading shipbuilding industry – including the Harland & Wolff yard that built the Titanic, which infamously sank on its maiden voyage in 1912. The same yard is now operated by the Spanish state-owned company Navantia, which has a contract to build Royal Navy fleet solid support ships.

The harbour growth plan would include reclaiming more land for the first time in 25 years to build a new container terminal.