A long-awaited review into business rates by the Scottish Government may not make any difference to the bills firms ultimately pay, the man in charge has admitted.

Ken Barclay, whose 12-month review is due to report in July, told MSPs his group had yet to decide whether to recommend “any final changes to any of the taxpayers” involved.

He also told Holyrood’s local government committee it was too early to say whether the review would produce “tinkering around the edges or a complete redesign”.

Several MSPs reacted to the former RBS chairman’s comments with surprise, with Green Patrick Harvie suggesting the committee had been “underwhelmed” by his evidence.

The SNP’s Kenneth Gibson also accused Mr Barclay of a “bizarre answer”, when he suggested public buildings could generate additional revenue by hiring themselves out.

“I don’t think police stations, fire stations and hospitals would raise much,” Mr Gibson said.

Nicola Sturgeon appointed Mr Barclay to lead the review last year.

She said the exercise would be revenue neutral, maintain the small business bonus scheme, and help make Scotland the best place to do business in the UK.

Mr Barclay, who left RBS in 2015 after 40 years, said it would be “an important piece of work”.

The review has since grown in political significance, with ministers relying on it to fix an outdated system whose flaws were exposed by a revaluation in the spring.

After pubs and hotels revolted at rises in bills of up to 400 per cent, ministers were forced to introduce a series of emergency reliefs for the current financial year.

Mr Barclay told MSPs the review had received 156 written submissions, taken oral evidence from 40 individuals, and was holding meetings with businesses around the country.

Despite the short time until it is was due to report, he said there were still 60 different lines of enquiry open, including whether rate bills should reflect business profits as well as property values, councils getting more power over rates, and firms being compelled to divulge more information to assessors under threat of a fine.

MSPs criticised the limited remit of the review, which referred only to businesses, despite public and voluntary sector bodies paying more than £1bn of the £2.8bn raised through Non Domestic Rates (NDR) for council services last year.

Labour vice-convener Elaine Smith said the remit might have put off some NDR-payers contributing, and asked if Mr Barclay was amenable to re-opening it.

Mr Barclay said he would take on board what the committee had said, and consider whether more time was needed, and agreed to accept late submissions of all kinds.

SNP convener Bob Doris asked Mr Barclay for “a degree of assurance” that he was talking to the NHS, councils, and police and fire services, given his recommendations could affect them.

Mr Barclay said they had "not yet been engaged in the process" but he would now consider it.

Mr Doris said the committee wanted a “more proactive approach” from the review to public sector bodies, adding: “We would rather get it right than fit in with a time-scale.”

Urging him to open up the review, Tory Graham Simpson told Mr Barclay: “If you’re going to do a review of the NDR system, it has to be the whole system, and not just focused on one aspect of it. Because if it is, you leave yourself open to huge criticism that you’ve not done a thorough review.

“If this committee was to do a review like that, it would be lambasted and rightly so."

Mr Simpson also asked Mr Barclay if his recommendations would mean a thorough redesign or “broadly what we have now with a bit of tinkering.”

Mr Barclay said: “It’s too early to say whether it will be, as you describe it, tinkering around the edges or a complete redesign.”

Mr Simpson replied: “You haven’t got a great deal of time left if you’re going to report by the summer, so it’s not that early, is it?”

Mr Barclay said later he still hoped to report to ministers by July, even if he had to consider the extra information suggested by MSPs.

Scottish Retail Consortium director David Lonsdale, who also gave evidence, said businesses would be “deeply concerned” if councils were given full control over rates.