A father and son today denied the manslaughter of a teenage farm labourer who was crushed to death inside a giant soil recycling machine in Bristol.

Roy Hill, 63, and his son Michael, 31, who run family business RE Hill and Son, allegedly failed to place a protective guard on the soil-sifter, which dragged 17-year-old Lee Mason to his death on April 4, 2007.

The accident happened at a farm in Dundry, owned by the Hill family, who run a skip hire business and livery on the site.

The men, both of Ridings Farm in Dundry, pleaded not guilty to manslaughter at Bristol Crown Court today.

Lee was crushed by the machine after getting his arm caught in the tail pulley.

It is alleged that the Hills failed to train the teenager in using the machine and allowed it to be used without a working tailguard.

Roy Hill also denied contravening the Health and Safety at Work Act by failing to ensure the safety of employees at the site with a proper system of supervision and training.

Michael Hill denied contravening health and safety law by failing to take reasonable care of employees.

Lee lived with his mother, stepfather and three younger brothers in the Knowle area of Bristol.

The case was adjourned to Tuesday afternoon.