The research paper, which highlights the benefits of diet drinks, was funded by the ILSI Europe research institute, whose members include Coca Cola, PepsiCo and Nestlé.
It has since emerged that researchers involved in the study were given a payment of roughly £750 each, which was never disclosed in the press release when the review was published, The Sunday Times reported.
The establishment behind the study, Bristol University, has defended its research saying that it was funded by a "range of bodies including the NHS and European Union, as well as ILSI Europe" and that it has been "peer-reviewed" by other scientists.
The review, which was led by Professor Peter Rogers from Bristol University and published in the International Journal of Obesity, suggested that diet drinks could be better for aiding weight loss than drinking water.
It analysed more than 5,500 articles but relied on just three of those articles to make the claim that diet drinks could be better than water for helping weight loss - two of which didn't find any significant statistical difference in weight loss between those who drank diet drinks and those who drank water while on a diet.
The research paper did disclose in the acknowledgements section that it had been funded by the Eating Behaviour and Energy Balance Task Force for ILSI Europe, whose members include Coca Cola and PepsiCo.
However it has since emerged that Professor Rogers, who led the study, is also co-chairman of the task force.
Meanwhile the published paper didn't disclose that some of the co-authors were paid fees of €1,000 (roughly £750) each.
A spokesperson from University of Bristol said they had not provided details of funding for "reasons of space".
They added: "This research was published in the International Journal of Obesity, a peer-reviewed journal, which means the data and conclusions have been scrutinised by other scientists.
"We therefore stand by the findings. It was funded by a range of bodies including the NHS and European Union, as well as ILSI Europe."
Nutritionist Charlotte Stirling-Reed said that it is important to be aware of the fact companies like Coca-Cola and PepsiCo have financially backed the study and people should consider this when weighing up the results.
"However, we also need to consider that there is limited funding available for research into diet and heath - something that we need on an ongoing basis, bearing in mind the health of our nation," she added.
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It's not the first time Coca Cola has made headlines for backing such studies.
Last August, it emerged that the company was providing financial and logistical support to a nonprofit organisation called the Global Energy Balance Network.
The network promoted the message that rather than focusing on diet, people should pay more attention to exercise.
For those considering drinking diet drinks as a way to lose weight, Charlotte Stirling-Reed advised that "water is always going to be a better source of fluid and hydration than a fizzy or diet drink".
"However, for those who consume a great deal of fizzy drinks, completely switching to water probably isn’t a realistic move," she added.
"Diet drinks can be useful as a transition from full sugar versions and may help fizzy drink consumers to reduce their calorie intake. However, reducing overall preferences for sweet foods, could also be an important step."
Research published in November 2015 found a link between consumption of diet drinks and increased risk in heart failure, particularly in men.
HuffPost UK Lifestyle has reached out to Coca Cola for comment and is waiting to hear back.
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