Wellington's Mt Victoria bus tunnel closed after bus struck by falling tree

It's believed the bus was hit by a tree at the entrance to the tunnel. Photo / Supplied

Wellington's Mt Victoria bus tunnel will be closed overnight after a bus was struck by what's believed to be a falling tree.

Wellington City Council spokesman Richard Maclean said no passengers were hurt in the incident, which occurred sometime between 3.30 and 4.30pm on Tuesday afternoon.

Council had initially feared the bus was hit by a falling section of the tunnel roof, but have since confirmed it was likely part of a tree.

"As far as we can tell, the trouble was more at the entrance and above the entrance to the tunnel, rather than in the tunnel itself," he said.

"But obviously whatever happened shouldn't have happened."

The bus has been removed from the bus tunnel, and the other Mt Victoria tunnel is operating as normal.

The tunnel will remain closed overnight, until engineers have inspected the site and the slope above the tunnel entrance tomorrow morning.

In the meantime buses to and from the eastern suburbs and the airport will be diverted through the main Mt Victoria tunnel.

Travellers are being asked to expect delays and allow additional time for travel on the Metlink app.

Maclean said there will be questions to be asked about exactly what happened, and any potential future risks need to be identified.

He said they will bring in their tree and geotechnical experts to inspect the slope above the tunnel entrance.

"Clearly if there is a problem with stability above the tunnel entrance, we're going to have to do something about it – even if that's removing the trees above it."