Stockton ferry grounded indefinitely, replacement buses in operation

Maintenance crews are working to determine the extent of mechanical issues with the Stockton ferry service after it was unexpectedly cancelled on Monday morning.

A spokesperson for Keolis Hunter, the operator of the ferry service, confirmed that replacement buses had begun transporting passengers between Stockton and Queen's Wharf every 30 minutes.

"We've got our maintenance team on site looking at it," they said.

It is unknown how long the MV Hunter will be grounded for maintenance.

Ferry failures and cancellations have plagued the Newcastle Harbour route over the past year.

Last November and December the ferry service was cancelled several times because of mechanical issues with the 40-year-old ferries.

At one stage the ferry service was out of action for almost a week.

It led to Premier Chris Minns issuing an apology to Stockton commuters and residents who rely on the service.

"I genuinely apologise for the delay. It has gone on far too long," Mr Minns said.

In May the NSW government announced a $5 million refurbishment program on the MV Shortland and MV Hunter over the next 18 months to make mechanical and technical improvements to extend the operational life of the ferries to 2036.

The MV Shortland is docked while it undergoes its refurbishment, and the MV Hunter is scheduled for its upgrade in August next year.

In August, Keolis Hunter announced an additional 19 ferry services each week after tweaking the timetable.