The NSW roads minister has admitted there is no completion date for the $3 billion M6 motorway in Sydney’s south, despite earlier advice from the state’s transport agency that it would open to motorists by late 2028 as work was more than 90 per cent complete.

Jenny Aitchison told the NSW upper house’s budget estimates committee on Friday that there was no opening date for the four-kilometre underground motorway between Arncliffe and Kogarah, which has been stalled by years-long delays and a stand-off between the government and the contractors. The stalemate ended in June when contractors agreed to resume major work on the final section, more than two years after a 10-metre-wide sinkhole opened up.

“At this stage, we don’t [have a date]. We’ve agreed with the contractor that they’ll optimise the delivery as much as they can. They’re on-site, and we’re working with them to do that,” Aitchison said.

Transport for NSW’s previous target date for the M6’s completion was the end of 2028, which is three years later than a previously planned opening in late 2025. But following questions from the Herald, the agency confirmed on Friday that a completion date has not existed ever since work on the motorway recommenced in June.

The transport department’s press release two months ago said it would “provide an update on the expected completion timeline in due course,” but did not explicitly state that a target opening date did not exist at all.

Coalition roads spokeswoman Natalie Ward said the public “should be able to expect some indication of a completion date, or at least a quarter” for the billions spent on the project.

“We’ve made it very clear to them [the contractor] what the expectations are. They had a design and construct contract to complete the project, and that’s what we expect of them,” Aitchison said. She conceded there was no updated cost or project completion date in the government’s budget papers.

It comes after a two-metre-wide hole emerged on Monday at Rockdale on the surface of the final 244-metre section of the motorway. Asked whether the latest incident risked stalling the project further, Aitchison confirmed it would “absolutely not”.

“There was a small washout, it was notified to Safe Work. It wasn’t actually a notifiable event. My understanding is it’s been addressed, so it’s all back on the track,” she said.

This masthead has previously revealed the government has seriously considered abandoning the project since the sinkhole incidents. The government has already shelled out $2.78 billion on the motorway, and has set aside a further $200 million this year for the project.

The M6, which will funnel motorists onto the WestConnex motorway at Arncliffe, will be tolled when it opens, but it will remain in government hands under the Minns government’s policy.