Union wants industrial manslaughter law

A powerful union has renewed its calls for an industrial manslaughter charge in Queensland following the deaths of two workers at Brisbane's Eagle Farm racecourse.

Ashley Morris, 34, and a 55-year-old colleague were killed instantly when a nine-tonne concrete slab fell on them in a pit at the track's infield.

Angry relatives are demanding answers, while the Brisbane Racing Club has described the incident as one of the saddest in its 150-year history.

Workers who saw their two colleagues killed have been offered counselling as police and workplace inspectors try to work out what went wrong.

The CFMEU's work, health and safety co-ordinator, Andrew Ramsay, says it's time Queensland had the power to lay industrial manslaughter charges.

He says the current fine system doesn't go far enough.

"The union has been pushing for it for years ... we have pursued it with government after government," he told AAP.

Racing Minister Grace Grace said the deaths were heartbreaking but she had full faith in police and Workplace, Health and Safety officers investigating the matter and expected a report quickly.