A train has derailed in South Otago this evening, blocking the state highway.

Fire crews are at what is known as the Clinton Railway crossing, that crosses State Highway 1.

A spokesman for the Fire Service said they were called to the scene about 7.40pm.

"It's right in the centre of town. We're assisting police at the moment.''

Advertisement

Police said the train involved was a freight train. It derailed between Gorge Rd and Nelson St just after 7.30pm.

There were no cars involved.

"Traffic is flowing okay, but one lane is blocked, on SH1 unknown which lane this is,'' a police statement said.

A KiwiRail spokesman said six wagons of the freight train - travelling north from Invercargill - had become derailed.

Just before 10pm, the spokesman said no wagons were blocking the road, except for the level crossing over SH1. The area was blocked off by barriers for some time.

"KiwiRail staff are on the way to the site and it is expected the derailed wagons will be cleared from the line tomorrow,'' he said.

Exactly how the train derailed is not yet known.