The supposedly coming-soon video on demand service from BBC Worldwide, ITV and Channel 4 has been referred to the Competition Commission by the Office of Fair Trading.
The OFT said the three-way team-up could mean Project Kangaroo would "charge higher prices in syndicating content to wholesale customers".
Following the OFT's decision, a joint statement has been issued from the BBC Worldwide-ITV-Channel 4 venture:
"We're naturally disappointed by the decision from the OFT and are frustrated that it will delay the launch of Kangaroo, however all parties remain committed to what the venture offers."
"The parties are confident that when properly subject to more detailed scrutiny by the Competition Commission, the Competition Commission will conclude that the joint venture will provide wider choice for consumers and be seen as a pro-competitive force in the market place."
"Our aspiration is that Kangaroo will offer a wealth of British content and provide an example of UK innovation and collaboration for the benefit of consumers and advertisers alike."
Once the Competition Commission process is complete, which could take 6 months, assuming it's a favourable outcome, each broadcaster will still need to go to its board for approval and the BBC Trust has to okay BBC Worldwide's involvement too.