Conservationists have raised concerns about the impact of Scotland's biggest live music festival on bats and red squirrels.

Scotland's national heritage body says it is not going to raise a formal objection to the staging of T in the Park at the Strathallan estate in Perthshire, but says the event may have impact on wild animals.

A report from Scottish Natural Heritage (SNH) says that DF Concerts plans to adjust its plans for the local animal population, including protected species such as ospreys will be "adequate."

But SNH has called urgent monitoring of the activity of otters, bats and red squirrels to adequately assess what impact the festival would have on these species.

The letter to Perth and Kinross Council concludes that the authority can "be confident that the applicants can meet the species licensing requirements set out above before issuing any planning consent, so that there can be certainty that the event can proceed in practice without risk of an offence being committed against protected species".

The festival has unveiled its line-up for the event, which takes place from July 10-12, with headline acts including Kasabian, The Libertines and Avicii.

The letter does raise other concerns.

SNH recommend it is essential that the required monitoring is carried out "without delay" on the activity of otter holts.

It says that 37 trees in the vicinity of the event area had "definite bat roost potential" but they need a proper survey.

SNH say the festival will have to follow up with another survey of potential bat roosts.

It also asks for a "thorough survey" of all potential red squirrel dreys within 100 metres of the event area as soon as possible.

A statement from DF Concerts said: "We're pleased that the mitigation plans we've put in place with experts have been recognised and SNH has no objections to the event taking place.

"We will ensure that we meet the conditions set and we'll continue to take guidance from the SNH going forward with the priority being that there is minimal disruption to any wildlife."

Organisers DF Concerts were forced to move to the castle due to safety issues associated with an oil pipeline at Balado, a site which was used for 18 years.

The letter from SNH says that the ospreys could still be affected by the festival.

"Whilst we agree that the proposed relocation is likely to be effective if ospreys use it, we advise that there remains a risk that the high levels of noise and the lighting effects during the event phase could still cause disturbance in practice. "Disturbance is also possible if the ospreys reject the new nest and choose instead an alternative location closer to the main disturbing activities."