The decision came after Antigua and Barbuda complained to the WTO last year that US prohibitions against internet gambling are discriminatory and in breach of international trade agreements that require the US to allow foreign internet companies to offer their services to US citizens.
The US responded that gambling on the internet is different from casino-based gambling, not least because of the difficulty in preventing children from accessing the services. It also said that the restrictions it has put in place do not in fact breach the trade agreements, which allow for exceptions for moral reasons, according to Reuters.
Finally, the US argued that when the WTO was set up in 1995, gambling services were excluded from its remit.
But the defence put forward by the US appears to have failed. Reuters reports that an unnamed US trade official has now confirmed that the final report has been issued, and is "largely unchanged" from a preliminary ruling in March that found the US in breach of the WTO rules.
"We intend to appeal and will argue vigorously that this deeply flawed panel report must be corrected by the (WTO) appellate body," said the official.
Antigua and Barbuda, with a population of less than 70,000, has an economy largely dependent on tourism, but with a growing market in internet gambling. According to a report on Caribbean Net News.com, the country has lost around US$30 million since the US began its attempts to restrict Americans' access to on-line gambling services.
The text of the ruling is not likely to be issued until the end of May.