The competition watchdog has formally raised “serious concerns” with Viagogo about its compliance with a court order secured to protect consumers.

The Competition and Markets Authority (CMA) said the secondary ticketing website must now address the concerns or face a return to court.

Viagogo claimed it had met last Thursday’s midnight deadline to comply with the High Court order requiring it to make a number of changes to the way it collects and presents information about tickets for sale on its site, in particular about seat numbers, resale restrictions and face value as well as to the way it uses messages about the availability and popularity of tickets.

A CMA spokeswoman said: “Having conducted urgent checks, the CMA has serious concerns that Viagogo have not complied with important aspects of the court order we secured against them.

“We have told Viagogo we expect them to make the necessary changes without delay. If they do not, we will go back to court to force them to do so. Severe penalties are available if they are found to be in contempt of court.”

Viagogo said: “We are compliant,” adding that this was the only statement it had at this time.

It is understood that the CMA’s concerns relate to the steps Viagogo has taken to implement these changes, specifically that important information, including seat numbers, is not always being collected from sellers and as a result may not then be displayed to buyers.

Other concerns are thought to relate to the appearance of information such as restrictions on resale and whether some messages about the availability and popularity of tickets comply with the order.

The CMA’s concerns follow its own monitoring of the site since the Thursday deadline and are in addition to an independent review of compliance with the court order.

In November, the CMA told the Switzerland-based company it must overhaul the way it does business to protect consumers under a High Court order.

Under the order, Viagogo must also publish the names and addresses of touts – those selling more than 100 tickets a year via the site.

The CMA began enforcement action against four secondary ticketing websites last November, with three of them – Stub Hub, GetMeIn! and Seatwave – committing to change their business practices.