A train driver stopped by climate activists this morning did not see three youths on the tracks until the train was ''dangerously'' close, police say.

Extinction Rebellion Ōtepoti activists have once again stopped a train carrying coal from leaving Dunedin Railway Station.

It follows another protest like it yesterday.

Three young activists stepped on to the rail track about 7.20am.

Senior Sergeant Craig Dinnissen said, this time, the train drivers reported that they had not seen the activists until the train was at a dangerously close distance.

''Climate change activists are again putting people at risk, this time putting 16-year-old youths on the track in hours of darkness.

''Once [the train] starts moving, they can't actually just stop.

''The protesters are endangering their lives, and the activists that are standing on the platform are encouraging them to endanger their lives as well.''

Extinction Rebellion spokesperson Dante Dawes said they were there to demand that KiwiRail stop hauling coal.

''The carbon dioxide emissions from this one daily shipment are the equivalent of putting an extra 80,000 cars on the road every day, more than enough to negate any promises KiwiRail has made to cut their own operating emissions.

''It is unacceptable that KiwiRail, a state-owned enterprise, be so complicit in the climate crisis and the destruction of our future.

''We feel solidarity with other young people all across the world who are fighting . . . That is why we have been an important part of the three previous actions on these tracks, and why we are prepared to do it again.''

They said the group had tried to engage in discussion with KiwiRail and written letters to its shareholding ministers, but felt their calls for action were not being answered.

A police spokeswoman said they were called to the protest at the Dunedin Railway Station at 7.45am.

About 10 protesters were in attendance, and at one point three of those people were on the train tracks.

''After speaking with police the three people removed themselves from the tracks.''

No arrests were made and police had not issued any trespass notices ''at this time'', she said.

The Otago Daily Times has contacted KiwiRail for comment.