COUNCIL executives have threatened to cancel Scotland's biggest pop festival if it repeats the failings of last year's event on a new Perthshire site.
The 2015 T in the Park, the first at Strathallan was widely criticised over transport problems, crowd safety issues and planning breaches.
A Perth and Kinross Council review said "confidence has been undermined" following DF Concerts' management of last year's event.
The council's review says the festival drew the largest number of post-event complaints in its 18-year history.
The report, by the council's director of environment services, Barbara Renton, states that the council will need "substantial" reassurance and evidence from DF Concerts that improvements have been made before officers can recommend that the festival gets the green light again.
The report concludes: "The problems experienced at the event were more attributable to a combination of "teething problems" on a new site, and deficiencies in the organisers' event delivery.
"As a result, council staff will need substantial reassurances and evidence from DF Concerts that detailed plans will be prepared on time, and the event will be delivered more effectively, before officers could have confidence in recommending that the event takes place at Strathallan again."
DF Concerts said it was "entirely focused" on delivering improvements.
The three-day festival, which attracts daily crowds of around 85,000, moved to Strathallan Castle after 18 years at Balado in Kinross.
The review by Perth and Kinross's Environment Service director Barbara Renton said 2015's event drew the largest number of complaints and negative comments in the festival's history.
Issues included "significant traffic congestion" with patrons taking several hours to leave the site and local road network on Saturday and Sunday nights and tailbacks for several hours during the day on Monday 13 July.
Principal issues highlight included concerns about patrons taking several hours to exit the site onto the local road network.
The report talked of significant traffic congestion for several hours during the day on Monday, July 11, both around the site and towards the Muthill area And there were safety concerns expressed over large numbers of pedestrians on unlit minor roads at night, in heavy traffic.
The report said there were perceptions of a general lack of crowd safety and security on site at the event.
Traffic chaos at T in the Park posted by Gordons Taxis of Bo'ness
"In addition, planning officers reported repeated breaches of planning permission conditions, which were, in officers views, not addressed with sufficient rigour by the applicant, or their agent," said the report.
DF Concerts said: "We're incredibly disappointed that, for the first time, we did not achieve the high standards of event management and customer service that we have set for ourselves which the council and our customers have, quite rightly, come to expect.
"We note all points of Perth and Kinross Council's report as published and remain focused on implementing key changes for 2016. We will not be disappointing ourselves, Perth & Kinross Council, the local community and especially our fans in 2016 and in truth, we look forward to being able to demonstrate that.
"We're entirely focused on delivering a fun, safe and successful festival that reminds everyone why T in the Park became Scotland's favourite music festival in the first place."
Problems at the T in the Park Slam tent