George Clooney has said he is “surprised and saddened” by the alleged discovery of child labour on farms used by coffee giant Nespresso, the brand for which he has long served as ambassador.

The Oscar-winning actor and director, who during school holidays worked on his own family’s tobacco farm in Kentucky, vowed that “work will be done” to improve conditions after a Channel 4 Dispatches documentary, due to air next week, filmed children picking coffee beans and hauling sacks on six Guatemalan farms believed to supply Nespresso.

“Having grown up working on a tobacco farm from the time I was 12, I’m uniquely aware of the complex issues regarding farming and child labour,” said Clooney in a statement.

“Clearly this board and this company still have work to do. And that work will be done.”

In response the company, which is part of Swiss conglomerate Nestlé and advertises its coffee as ethically sourced, has launched a “thorough investigation” into its farms in Guatemala and suspended all purchases from the problem plantations.

“Nespresso has zero tolerance of child labour,” said Guillaume Le Cunff, the Nespresso CEO, in a statement.

“It is unacceptable. Where there are claims that our high standards are not met, we act immediately.

“Any issues we uncover will be dealt with diligently and firm action will be taken. We work with Rainforest Alliance and Fairtrade International to reinforce good working practices and fair treatment of workers, including education on the dangers of child labour.

“We will continue to do all we can to stamp child labour out. It has no place in our supply chain.”

Despite numerous corporate-led and third-party audit visits to Nespresso’s coffee farms in Costa Rica, Ethiopia, Uganda and other supplying countries, only two cases of child labour were reported in 2019, according to Nespresso. Fifteen cases were reported over the past four years, although none of them were in Guatemala, and each one was “effectively resolved”, the company said.

However, Le Cunff admitted that its coffee suppliers are given “a day or two days” advanced notice when spot checks take place.

In his statement, Clooney, who has been the public face of the coffee company for the past 14 years and sits on Nespresso’s sustainability advisory board alongside the NGO Rainforest Alliance, Fair Trade International, and the Fair Labour Association, said he was “enormously proud of the success of [Nespresso’s] efforts” in “improv[ing] the lives and livelihoods of farmers all around the world”.

But he admitted that investigative journalism played an “imperative” role in pointing out Nespresso’s failures and that more needed to be done to bring the company in line with its ethical standards.

“The check and balance of good corporate responsibility lies not just with the company itself but also independent journalists like [Dispatches reporter Anthony] Barnett to hold everyone’s promise to account.”