Transport Minister Michael Wood says the opening of Transmission Gully will likely be delayed again due to the latest Covid-19 lockdown.

It's the latest blow to the troubled $1.25 billion road project, which has already been the subject of budget blowouts, delays and bailouts.

Wood appeared before the Transport and Infrastructure Select Committee this morning.

He said alert level 4 restrictions were having a significant impact on the transport sector.

"We don't have any particular get out of jail free card or exemption."

Wood said there would likely be an impact on the completion date of Transmission Gully as a result.

"It's a little bit early to be specific around what that might actually mean."

The four-lane motorway is being built through a public-private partnership (PPP), the Wellington Gateway Partnership (WGP), with CPB Contractors and HEB Construction subcontracted to carry out the design and construction.

More to come