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

But Roy Hill, 63, and his son Michael, 31, who run family business RE Hill and Son, were found guilty of health and safety breaches.

Lee Mason, 17, was dragged to his death in a soil-sifter on April 4, 2007.

His left arm was caught between a belt and a roller of the machine which turned excavated material into top soil.

Mr Mason, from Knowle, Bristol, was pulled in by the rollers which crushed his neck, killing him. He was just three weeks away from his 18th birthday.

His body was found with the machine still running and the guard, which would have prevented his hand becoming trapped, on the floor nearby.

The accident happened at Bridgwater Farm, in Dundry, near Bristol, property owned by the Hill family, who run a skip hire business and livery on the site.

The men, both of Ridings Farm in Dundry, were cleared of manslaughter at Bristol Crown Court today.

But the jury found them guilty of breaching health and safety rules by allowing Mr Mason to work on the machine without training or supervision and allowing the machine to be operated without a guard that would have protected the teenager.

Roy Hill previously admitted a separate charge of contravening health and safety regulations in not undertaking a risk assessment.

The Hills are to be sentenced tomorrow.