Light-rail tunnel preparation work has stopped after workers uncovered what police confirm are human bones at the site.

Workers stopped digging at Queen Street after they discovered human bones Thursday morning. (Amanda Pfeffer/CBC)

The bones were discovered this morning at 66 Queen St., near Metcalfe Street, as contractors worked to replace water mains on Queen ahead of next year's planned work on the LRT.

Police said late Thursday afternoon the bones are human and they're looking into whether the area is a historic gravesite.

A police identification team has contacted the coroner's department and sent images to forensic anthropologists in Toronto for identification.

Police will have to give workers permission to get back to work.

Area holds cemeteries from Ottawa's early days

The city has been replacing water mains on Queen Street in advance of next year's work to tunnel under the downtown to make way for light-rail trains to pass underground.

The light-rail system is expected to be up and running in 2018.

City archeologists have previously conducted digs at known archeological sites such as LeBreton Flats.

Since it's one of the oldest parts of Ottawa, construction workers in the downtown core have turned up remains in former cemetery sites before.

For example, workers digging near the National Arts Centre in the 1970s uncovered skulls that rolled down the hill when they were dislodged.