A Dutch music festival that became a “super-spreader event” may have allowed entry to hundreds of people already infected with Covid-19.

The Verknipt festival in Utrecht, attended by 20,000 people, saw more than 1,100 visitors test positive for Covid-19 in the days following its staging at the start of July. The Dutch Government has once again banned multi-day events since Verknipt was held.

Now, according to a De Volkskrant story, a report by the local health authority, after interviewing 400 of those who subsequently tested positive, has found that a third – 130 people – of those already had the virus before attending despite mandatory testing prior to entry.

Dr Putri Hintaran, of the public health service (GGD) of Utrecht, said information collected in the weeks since suggests that fewer people than initially anticipated actually contracted the virus at the festival. However, the number who were able to enter while already infected is a concern, with the decision to let tests be taken up to 40 hours prior allowing people to catch the virus before arrival.

Researchers found that many infected festival-goers had attended multiple other social festivities earlier that week and may have become infected there.

Reza Fathi, founder and co-owner of the Verknipt festival, said organisers had adhered to all local authority protocols, and believes the GGD findings vindicate their actions.

“The OMT and Fieldlab recommendations about maximum test duration were ignored and young people were allowed to dance with all the associated consequences,” he said.

In a Facebook post, organisers added: “We discussed the permit until just before the event with the municipality of Utrecht to the detail about the permit and especially looked at all the corona measures. This resulted in a 45-page document containing additional corona protocols, in addition to existing safety measures.

“We have strictly checked for QR codes and IDs. However, we couldn’t see if people who had received a Jansen vaccination, recovery license or Testing for Access based on QR codes.”

Last week, the Dutch Government banned all multi-day events until August 31 following discussions with the Alliance of Event Builders and others. The ban applies to multi-day events that include overnight stays, for which visitors would have required a coronavirus entry pass.

A Government statement read: “Organising multi-day events safely and responsibly is complex. Industry representatives themselves state that this is currently not feasible for multi-day events planned in the second half of August.”

A spokesperson for Mojo, which organises Lowlands and Mysteryland, said: “Unfortunately, the Alliance together with the Government had to conclude that we have now been overtaken by reality and that this has become an unfeasible scenario.

“The quality and responsible festival experience for visitors, employees and artists cannot be sufficiently guaranteed. That is of course a very sad statement and a bitter pill for the industry that has been closed for so long.

“But at the same time, the Alliance understands and respects the decision that the multi-day camping festivals cannot continue until September 1.”