A series of concerts held in a popular park in Cardiff went ahead without planning permission, a council report has said.

The performances on Blackweir Fields from Noah Kahan, Alanis Morissette, Slayer and Stevie Wonder saw tens of thousands of people attend.

The Cardiff council report stated there was no application for planning permission in the run up to the shows, and that a certificate of lawfulness, which shows whether planning permission is required or not, had not been issued.

The council said it had decided not to take formal planning enforcement action against the organisers.

The series of gigs known as Blackweir Live had received complaints from residents, who set up a petition about large fences being erected around the site.

Cardiff council said the concerts would bring £35m to the city’s economy, which would be used to improve parks and infrastructure.

The report said there was no planning permission application before the events took place, and without a certificate of lawfulness, the organisers Depot Live and Cuffe and Taylor were “proceeding at risk”.

Planning laws prohibit a temporary change of the use of parks for more than 28 days each year without additional planning consent, but the report found that the area of Blackweir Fields was affected for a total of 37 days, nine days more than allowed.

The report highlighted a case in London earlier this year, when a resident successfully took her local authority to court, arguing Lambeth council did not have the correct planning permission to stage events in Brockwell Park.

The report said: “There have been no other temporary events in Blackweir Fields during this calendar year, but the result remains that the number of days exceeds that permitted.”

Council officers considered whether enforcement action should have been taken, but recommended “it would not be expedient for the council to take any formal enforcement action against the event organiser”, calling the breach “minor”.

The report concluded both Cardiff council and the organisers of any future events should apply for planning permission for any event exceeding the 28-day limit.

Cardiff council said the decision against Lambeth council was made after the Blackweir Live gigs had been approved and booked.

It also added an events licence had previously been granted for the concerts.

It said: “While the setup and breakdown of the site exceeded the 28-day limit for temporary events, the concerts themselves stayed within that timeframe, which was why planning permission was not sought for such a temporary event.

“The implications of the recent court judgement will now form part of a wider review of arrangements for future events in Cardiff.”

The organisers Depot Live and Cuffe and Taylor have refused to comment.