Auckland's mayor has lost confidence that the City Rail Link will be finished on time, despite assurances from officials.

The City Rail Link project is set to cause major disruption for Aucklanders over the next year, as it hurries to finish work in time for opening in 2026.

The Minister for Transport recently announced Auckland's railway system would be shut with no running trains for up to 96 days between December 2024 and January 2026, to make time for crucial rail rebuild work for City Rail Link.

Auckland mayor Wayne Brown said the project had been marked by budget and time blow-outs.

He was asked if City Rail Link - set to open in 2026 - would be his last big project as mayor.

"That project has had a terrible track record. It was supposed to have finished before I became the mayor, and it was supposed to have cost a third of what it has cost," he said.

"I've kind of lost confidence in hearing back from the people that that's what's going to happen. It requires intense pressure at this stage. It's quite a good project, but it was set up very poorly."

Brown said it was disappointing City Rail Link had not been finished, but he was determined to get it across the line.

In a joint statement from Auckland Transport, City Rail Link and KiwiRail, the agencies said they remained confident about opening in 2026.

"There's a lot of work underway between AT, City Rail Link Ltd and KiwiRail to complete work on City Rail Link and across the wider Auckland rail network to be ready for more frequent, faster and reliable trains and we remain confident about opening in 2026."