The HSE has urged farmers to be aware of the dangers of handling bales after a woman was killed.
A woman has died after being hit by a falling bale on a farm in Glamorgan, South Wales on January 24.
It is believed her teenage daughter was also seriously injured in the incident and is in a critical condition in hospital.
The Health and Safety Executive (HSE) has confirmed it is investigating.
Adrian Hodkinson, HSE head of agriculture health, said: "This was a very tragic incident and our condolences go out to the woman’s family and friends.
"We are in an ongoing investigation with the police but at the moment we do not know the full circumstances."
Mr Hodkinson said farmers must always be aware of the dangers of working with bales.
"Big bales weigh more than 600kg - they are heavy things," he added.
"It is important they must always be handled by mechanical equipment rather than manually.
"If you want to break them up for use in feed or bedding they must be carefully de-stacked and only handled when safely on the ground."
For more HSE advice on working with bales, click here.