The number of people to speak out on plans to convert the old Royal High School in Edinburgh pushed 2,000.

The plan surprised 500 more since online comments were extended on the contentious idea to turn the building into a hotel was extended after the volume of traffic hit Edinburgh City Council’s computer system.

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Among those to speak out against the plan is author Alexander McCall Smith who is said to want to save Edinburgh’s “fragile beauty” from inappropriate development.

Sarah Boyack, Labour Lothians MSP, joined those calling for a rival plan for the Thomas Hamilton masterpiece on Calton Hill to be considered.

Marion Williams, of the city’s heritage group the Cockburn Association, said: “It is important that the building be brought back into permanent use but this is not the development to do this and we look forward to an alternative, waiting in the wings, that will provide a more sympathetic, long term solution for the site.”

However those who back the plan say it will revive the building and bring jobs and wealth.

The council's planning portal was hit by the rate of comments and the deadline for submissions was put back, inviting further submissions.

The rival Royal High School Preservation Trust is pushing to move St Mary’s Music School into the building with a cash offer of £1.5 million.

The building’s owner, Edinburgh City Council, said it is under conditional lease as part of the £75m plan to convert the A-listed structure into a hotel, led by Duddingston House Properties and Urbanist Hotels.

Ms Boyack, who is environment spokeswoman for Scottish Labour, has described the building as a “national treasure”.

She said residents have “objected to plans to develop it into a luxury hotel on the basis that it would irrevocably damage Edinburgh’s renowned outstanding universal value and world heritage status”.

The developers declined to comment, but David Orr of the Urbanist Group, who brought Harvey Nichols to Edinburgh and was the driving force behind the Mint Hotel Group, said earlier the proposals for the former boys' school - which opened in 1829 but unused since 1968 when the school was relocated, would create "a world-class new accessible destination for Edinburgh locals and visitors alike".

More than half of the 580 visitors to an exhibition at the site completed a feedback questionnaire which revealed that 79 per cent of them were generally in favour of the redevelopment proposals, with over 75 per cent agreeing that a world-class hotel would be an appropriate use for the well-known Edinburgh landmark.

The new six-star hotel would have Hamilton's restored building and when operational the hotel could create 640 local jobs and contribute on average £27 million annually to the local economy.

Architect Professor Gordon Murray has supported the first stage of the hotel plan, saying "in embracing Thomas Hamilton’s original Royal High School the contemporary architecture proposed here has a hard task remaining low key and a lot to live up to in quality but the ingredients are right and a fitting start has been made".

While the figure is high, it is not unique in the area, with a housing development at the former Craighouse university campus attracted around 4,000.