A wave of high-profile labour problems in the British fruit industry is simply due to teething troubles, according to one of the farms at the heart it.

The comment was made by Gilbert Savoury, HR director for major Herefordshire strawberry grower S&A Produce.

The 2,000-acre farming business found itself at the centre of fresh allegations of abusive labour practices, sparking a wave of investigations by the Home Office and customers including Sainsbury and Tesco.

The Transport and General Workers' Union staged a picket on Monday, saying it had received hundreds of complaints about 14-hour days in the heat with little rest and charges for medical treatment.

TGWU deputy general secretary Jack Dromey said: "S&A has refused to act so we had no option but to alert their customers. We welcome the supermarkets' investigations, but the pressure is still on S&A to stop the exploitation."

The union was due to meet representatives from S&A to explore their concerns, but a spokeswoman said supermarkets also had to take responsibility.

"What appears to be happening at S&A is part of a wider problem, where supermarkets are contracting and sub-contracting production, which puts a lot of pressure on suppliers."

S&A denied the charges and said investigators given free rein to explore the company's farms had turned up no problems.

"There's always room for improvement employing people on this sort of scale, but we are confident there are no foundations to these allegations," said Savoury.

He blamed disgruntled workers for the complaints. "We employ nearly 3,500 people and there are bound to be some who refuse to work. The wider problem is a significant influx of labour over the past two years. It is a bedding-in period."

Tesco and Sainsbury said they would stand by the grower unless their investigations substantiated the union's charges.