One of the two men who died when a wall collapsed at a Hunter Valley coal mine was apprehensive about working underground.

Phillip Grant once told a friend he was worried about working underground.

The young father was one of the two coal miners who died when a wall collapsed and buried them at a NSW Hunter Valley mine on Tuesday night.

Grant, 35, from Maitland and 49-year-old Cessnock resident Jamie Mitchell were working 500m below the surface and 10km along the Austar Coal Mine in Paxton when a wall collapsed at about 9.50pm on Tuesday.

Workmates tried to save them but were forced to leave the mine because of safety fears.

A rescue mission was launched in the small village but both men were pronounced dead just after midnight.

Mr Grant’s friend and neighbour, Aleisha Eslick, said the young father was aware of the dangers associated with mining.

“He mentioned a few things. I can’t think of anything specific, but I think just being underground worried him,” she told News Corp Australia.

“You couldn’t not be worried about it.”

Mr Grant’s parents on Wednesday travelled from their hometown of Bathurst to meet with authorities.

It’s understood Mr Mitchell had been a coal miner in the area for many years.

Mine rescue teams on Wednesday began a delicate operation to recover the men but police have warned it could take a number of days to bring their bodies to the surface.

“There is a fair bit of equipment and coal in the area that needs to be removed to be able to get access to them,” Superintendent Garry O’Dell said.

The Construction, Forestry, Mining and Energy Union (CFMEU) said miners all over the country would be affected by the deaths.

“Each and every one of them will be feeling it at the moment, particularly in the underground sector,” northern district president Peter Jordan told AAP.

“You cannot just accept the fact that it’s a dangerous industry and these things happen.”

The most recent mine fatality in the Hunter region was in December when a female trainee in a four-wheel drive was crushed by a 400-tonne coal truck.

The Austar Coal Mine will remain closed indefinitely – except for work maintaining safety – until the bodies are recovered.