The boss of T in the Park has claimed nesting ospreys cost the festival around £1m a year.

A war of words has erupted between organisers DF Concerts and Events and the Royal Society for the Protection of Birds (RSPB) Scotland over the site at Strathallan Castle in Perthshire.

DF Concerts and Events chief executive Geoff Ellis claimed his company has faced the increased costs because of "onerous" and "inflexible" planning conditions associated with the birds of prey.

RSPB Scotland responded to the statement, saying the birds had successfully fledged chicks "in spite of, rather than due to" the festival organisers.

Mr Ellis raised the costs associated with the ospreys as his company released its most recent accounts, which showed its profit before tax had fallen from £6.2m in 2014 to £3.5m last year.

He said: "It's probably obvious to observers that moving site for one of the world's biggest music festivals would cost significant amounts of money - we were clear about this at the time of the move and it's why we asked for help.

"The already high costs of the move were further, and significantly, increased by the late discovery of an unregistered osprey nest which in itself has brought about an annual increase in operating costs of around £1m per annum.

"It is ridiculous that these additional costs are due to the fact that we are constrained by and required to comply with onerous, inflexible full planning conditions - most of them not relating to the osprey but that are only necessary because of the osprey. It really does beggar belief."

Mr Ellis added: "The sad irony is that we have now proven for two years, beyond all doubt, that the osprey does not only exist but actually successfully thrives alongside one of the world's biggest music festivals.

"But still we are treated the same way for a temporary event on one weekend as if we were a permanent development.

"I'm all for the protection of wildlife - and the osprey are never more protected than when the festival is on - but the impact on the festival as a result is beyond comparison."

In 2015, doubt was cast on whether or not the festival would go ahead in its new home after it moved from Balado near Kinross due to the presence of the nesting ospreys at the site.

Perth and Kinross Council gave the event the go-ahead, however, after agreeing several conditions associated with holding the festival.

RSPB Scotland director Stuart Housden said: "There is no reason why T in the Park and ospreys cannot continue to happily coexist.

"This has been evidenced over the past two years when the birds have successfully fledged chicks. However, in this case it has felt as if this has happened in spite of, rather than due to, the efforts of DF Concerts.

"It is worth remembering that they initially tried to scare the birds away from the site and have appeared reluctant to agree to minimal measures to avoid disturbing these nesting birds.

"Our experience of working with DF has shown them to be like the stage act that has many plates spinning simultaneously- deadlines overlooked, corners cut, promised reports not being sent."

He added: "Perhaps it would be prudent to examine their working practices in an effort to reliably establish cause for the drop in profits rather than looking for a vulnerable scapegoat - one that seemingly has great value to everyone but them.

"We sympathise with well-meaning festivalgoers and artists who rightly want and expect their music festival experience to happen in sympathy with the natural environment.

"Working to create an exemplar of best green practice in the music festival business would surely benefit all concerned."

Earlier this year, the festival was given an entertainment licence for July's event despite objectors expressing concerns about the site.