New figures show it has lost nearly 3,000 members since 1993 and 15.5% of its income since 1996. Its current membership is about 7,000.
In a newsletter, MPO describes the situation as 'rapid and potentially disastrous decline'. It says if this continued 'the union which remained would find it difficult to represent its members'.
Communications manager Martin McGrath denied the union had failed, although he admitted a recruitment drive in 1998 had come too late. But he said: 'The work MPO does and the fact that we are extraordinarily busy representing senior officers shows there is still a need for that. What the NEC has decided is it's not reasonable for that to happen on its own.'