Past presidents of the RIBA have described the institution as "curmudgeonly" and "paltry", after it withdrew their complimentary tickets for events such as the Gold Medal and the Stirling Prize.
They say the decision shows a lack of respect and could result in several former presidents refusing to donate their collections of drawings and models to the RIBA library.
Current president Jack Pringle wrote to the past presidents on 7 December, telling them that they would not receive a complimentary ticket to next month's Gold Medal dinner unless they had served in the past five years. He said this was because of the cost of staging the event and the increased demand for paid tickets. He said they would still take priority when it came to booking.
Pringle said: "We now need to focus the complimentary places on the external people whom the RIBA most needs to influence, such as politicians, current donors and potential sponsors and benefactors of the RIBA Trust."
Past presidents dispute these arguments, noting that the RIBA would save about £1000, excluding VAT, from the Gold Medal dinner.
One past president said: "I worry about the RIBA's financial stability if it so desperate that it needs to nick a grand off us. I don't mind paying the cost of a ticket but I do think the RIBA pays a bigger price by being curmudgeonly."
Owen Luder, who served as president in 1981-83 and 1995-97, is understood to have written to Pringle echoing this view. He told Building: "It is not an issue of whether we can afford a ticket. It is just that it is such a paltry and short-sighted decision."
Another past president said it could affect his decision to donate his drawings and collection.