The news comes following the discovery in Pennsylvania last week of a mass grave, which archaeologists believe holds the bodies of the missing men.

A team, led by Dr William Watson from Immaculata University in Pennsylvania, found the grave at 'Duffy's Cut' by using thermal imaging and ground-penetrating equipment.

"The cavity is 40 feet long and 20 feet wide and just over five feet below the surface, " Watson told the Sunday Tribune. "It's covered with flat slabs of stone, which we believe were placed on the grave to keep animals from eating the bodies."

The missing Irishmen, originally from Donegal, Tyrone and Derry, left Ireland in 1832 to work as labourers in the United States. On arriving in Pennsylvania, they got employment constructing the Philadelphia and Columbia Railroad.

Six weeks later, they were all dead.

Because the men weren't citizens, no death certificates were ever filed.

It is thought all 57 workers perished in a cholera epidemic that swept through Delaware Valley that year, taking 900 lives and causing widespread panic.

However, there have been consistent rumours over the past century that some of the men may have been murdered by locals.

"We know for sure that some of the group contracted cholera, and that the healthy workers then tried to leave the valley, " said Watson. "There is evidence that these men were forced back into the valley by a local vigilante group. What we don't know is whether all the men were left to die from cholera, or whether some were actually murdered."

Watson pointed out that no other cholera outbreak had claimed the lives of every person in an area, with casualty rates normally between 40% and 60%. He said the remains of each of the workers will be examined closely for signs of a violent death.

"We hope that the retrieval of the bodies will solve this mystery, so we'll be looking for bullet-holes in the skulls or other evidence of violence to the bodies, " he said.

There is a possibility that the grave will be declared a crime scene if it is determined that some of the men were murdered.

As well as establishing cause of death, Watson plans to use DNA technology to track down any living relatives of the men in Ireland.

"We have tested the acidity in the soil and found that it should not have affected the DNA in the bones, " he said. "So we are very hopeful that we'll be able to trace the men back to Ireland."

The West Laurel Hill Cemetery in Bala Cynwyd has already offered to provide burial places for the men, and a special funeral mass will be arranged to commemorate their deaths.

Watson said the dig will get a big boost this week with an influx of archaeology students starting the autumn college term. He expects that the men's bodies will be exhumed in the coming weeks.

"It's been a very long search, " he said.

"We've been digging blindly since 2004, finding Irish artefacts like pipes and flags. But now we know we're close and it's very exciting."