A naked man has been hit by a bus in the Mt Victoria bus tunnel in Wellington.

Inspector Paul Jermy said the man was walking or running through the tunnel about 4:45pm when he was struck.

The man was being taken to Wellington Hospital with serious injuries, an ambulance spokesman said.

The exact nature of his injuries was unknown but they were not believed to be life-threatening, police said.

"He seems to have been able to express his dissatisfaction at being hit," Mr Jermy said.

The tunnel will be closed while emergency services attend the scene.