Commuters stuck in 'heat box' for 5 hours

A mechanical issue has left dozens of passengers stranded for more than five hours on a train in northern NSW.

The NSW TrainLink's Sydney to Armidale and Moree service broke down just south of Muswelbrook about 1pm on Friday.

Commuter Brian Kent says the six-carriage train has no air-conditioning or bathrooms.

"We've just been sitting in this heat box for hours and this place is packed to the rafters," he told AAP.

"There's a lot of elderly people here and one lady has already started to suffer a bit of heat stroke," he said.

NSW TrainLink said the train was in an area which is difficult to reach via bus.

"A locomotive will tow the train to Muswellbrook where coaches will transport customers to their destinations," a spokesman said.

Attempts to fix the problem are continuing, he said, with staff on board working to keep customers as comfortable as possible.

The passengers were picked up and transported to Muswellbrook about 6pm, TrainsLink NSW later said.