Developers behind the proposals, Duddingston House Properties and Urbanist Group, unveiled a scaled-back vision for the site in February after an initial bid was rejected by a single vote in December 2015. Councillors had decided the original plans, which included two six-storey extensions, would damage the setting of the A-listed neoclassical building on the flanks of Calton Hill.

Under new plans, the £70 million Hoskins Architects-designed project proposed 127 rooms, 20 fewer than originally envisaged.

However, council planning officials have now said it would harm the historic nature of the site and the landscape of the city and have recommended that councillors turn down the hotel plans when they meet next week.

In their report, Edinburgh planning officials said the 19th-century neoclassical building was an “architectural masterpiece”. The hotel plan failed to provide the “world-class” designs the site needed, they said.

Planners objected to two new five-storey bedroom wings on the grounds, which they said would interfere with the building’s historic character.

The hotel would have required the demolition of the entrance lodge and gym, which the officials said could not be justified.

The report said: “The former Royal High School is an architectural masterpiece and one of the most significant buildings in Scotland.

“The proposed wings would have a significant adverse impact on the composition, integrity and special character of the listed building.

“The benefits to the city’s economy and to tourism through bringing an ‘at-risk’ building back into a sustainable long-term use are not outweighed by the very significant harm to the built heritage and landscape of the city.

“The development would cause permanent and irreversible damage.”

A rival vision by Richard Murphy Architects and Simpson & Brown to turn the Thomas Hamilton-designed property into a music school has been approved but cannot proceed until an agreement between the City of Edinburgh Council and Urbanist Group expires.