(CNN Business) Oscar-winning actor George Clooney says Nespresso still has "work to do" after an investigation claimed to uncover child labor at six of its suppliers in Guatemala.

The 58-year-old star, who has been the company's brand ambassador since 2006, said he was "surprised and saddened" by allegations made in an upcoming episode of the UK documentary series "Dispatches" for Channel 4.

George Clooney has been the face of Nespresso since 2006

Journalist Anthony Barnett was given access to farms in Guatemala, which is the world's 10th largest coffee producer. Footage obtained appeared to show children working for up to six days a week picking beans on plantations and moving heavy loads.

The documentary is set to air on Monday.

Addressing the investigation's findings in a statement sent to CNN, Clooney, who is a member of Nespresso's sustainability advisory board, said: "We knew it was a big project when it started 7 years ago, and honestly, I was surprised and saddened to see this story. Clearly this board and this company still have work to do. And that work will be done."

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