All four honorary presidents - former Scots Makar Liz Lochhead, Douglas Dunn, Michael Longley and Aonghas MacNeacail - resigned in a joint letter saying they were “deeply unhappy” with its current management and governance.
It is claimed that 13 members of staff have left since the appointment of current director Asif Khan three years ago, which is said to represent almost 100 per cent turnover was described as "disastrous and wholly indicative of systemic management failures."
In their joint statement, the former staff members - Gillian Hamnett, former library services development and retail manager, Elizabeth MacGregor, former assistant librarian, Julie Johnstone, former librarian, and Nigora Asaeva, former library assistant - said they had felt "obliged to speak out to preserve the SPL’s reputation and future."
They have accused the SPL's board of failing to protect its staff from "unacceptable levels of distress and declining health" and of wasting time and money on "an ineffective restructure and appointing external consultants to address managerial issues."
The SPL has been plunged into crisis two years after more than 20 of Scotland's leading poets raised concerns about the library's hierarchy and referred to it as a "scene of unhappiness."
Jackie Kay, the current Scots Makar, and Carol Ann Duffy, the former UK poet laureate, were among those to sign a letter expressing a “real sense of concern” about the direction and management of the Edinburgh-based library , which was set up in 1984 and moved into purpose-built premises near the Scottish Parliament 20 years ago.
The library's board is chaired by Jane Ryder, who also chairs the Historic Environment Scotland Agency and is a former chief executive of the Office of the Scottish Charity Regulator. Other board members include the poets Stuart Paterson and Nuala Watt.
Lochhead, Dunn and Longley are all previous winners of the Queen’s Gold Medal for Poetry Award, while Gaelic poet MacNeacail was one of the library’s original founders.
Their letter, which has been seen by The Scotsman, states: “We, the undersigned, wish it to be known that, with great sadness, we have resigned as the four honorary presidents of the Scottish Poetry Library.
“We have done so because we are deeply unhappy with the current management and governance of the Library.”
The statement from the former members of staff said: "The library is adrift.
"It has little effective or inspirational leadership, and it has lost a wealth of staff experience and expertise which left newly joined and capable staff without adequate continuity or handover, often in constricted versions of the original role.
"We join other sector voices to protest at the current management and governance of the library, in the hope that appropriate working conditions are established for current and future staff to help the SPL implement its mission for Scottish poetry."
A statement from the SPL board said: “This is a disappointment but it’s their decision. We’ve worked hard over the last year to bring the library’s governance into the 21st century and are certain that this work will strengthen the library for years to come.”
Mr Khan said: “I have continued confidence, and indeed admiration, of the good work, dedication, effort and commitment of the board, staff and volunteers to modernise and diversify the governance and services of the library.”