A month ago, the planning body warned that its capacity at board level had “significantly reduced over recent months”, with just five functioning board members out of the standard complement of 10.

It noted that housing minister Darragh O’Brien had “recently announced that he intends to appoint at least three new temporary board members in the near future in order to restore capacity at board level”, which will “enable the speedier processing of cases in the first half of 2023”.

However, Friends of the Irish Environment (FIE), which has won a number of judicial reviews against the board in the last five years, has said even a full complement of 10 members “would be unable to address the backlog that has developed”.

The charity has called on the government to urgently implement an action plan published by An Bord Pleanála in October 2022, which recommends that the board should be expanded to 15 members through legislation.

Tony Lowes, director of FIE, said: “The backlog has become so acute that we have had to issue warning letters to landowners engaging in unauthorised site clearance as confident developers tire of awaiting the results of appeals.

“Another issue now increasingly arising through these delays is that the board must take into consideration the development plan in effect at the time of the decision, not the plan in effect at the time of the application.”

Law firm FP Logue, which acts for FIE, has highlighted that 21 applications in Fingal encompassing thousands of homes are still up for decision with a new development plan due to take effect in the area in April 2023.

FIE has also complained that it was recently told a decision in an appeal the charity lodged in June 2022 will not be made by the promised date of 16 January 2023, but has not been given a new date by which to expect a decision.

Mr Lowes said: “The law is very clear. The Planning Acts state that the board must ‘inform those parties of the reasons why it would not be possible or appropriate to determine the appeal or referral within that period and shall specify the date before which the board intends that the appeal or referral shall be determined’.

“When the Covid pandemic arrived in early 2020, the government moved with admirable expedition to introduce measures to ensure the maintenance of the functioning of the planning system during the pandemic.

“It is frustrating that appointments to the board in line with the recommendations of the action plan remain to be made while they are now unable even to meet basic legal requirements.”