Health authorities have been accused of diverting money that was ring-fenced for the mental health sector into paying for cost over-runs in other parts of the health service.
Under the Government's new mental health policy, A Vision for Change, it pledged to spend a minimum of an additional €25 million in day-to-day spending on developing mental health services.
However, campaigners in the Irish Mental Health Coalition say that most of this money has not been spent and that much of it has been used to pay for budget deficits in the primary and continuing community care sector.
It also says there is no sign that an additional €25 million in funding has been set aside for mental health services next year.
The group fears that the apparent funding shortfall will mean that the mental health sector - long considered the "Cinderella" of the health service - will continue to remain underfunded and underdeveloped.
John Saunders, director of Schizophrenia Ireland and chairman of the Irish Mental Health Coalition, said: "We demand from the HSE a clear financial account of where the money has gone.
"In the interest of openness, transparency and accountability we intend pursuing this relentlessly through the freedom of information legislation."
However, a spokesman for the health service said development funding provided last year and in 2006 was spent solely on improving mental health services.
"Resources were assigned to each local health office under a range of specialities during 2006 and 2007 and investment was used to recruit additional mental health staff," the HSE said in a statement.
"[During this time] 240 additional staff have been recruited. This includes 16 consultant adult psychiatry positions, six consultants with a special interest in rehabilitation and three consultants in the psychiatry of old age as well as one consultant psychiatrist with a special interest in psychotherapy."
The spokesman added that next year the health service would continue to meet the requirements of A Vision for Change and would be recruiting more consultant child psychiatric staff, as well as staff to facilitate the commissioning of additional bed capacity for children.
But the Irish Mental Health Coalition says statements from the HSE do not say how much has been spent on mental health, and how much additional money will be allocated for the sector next year.
It says that a ban on recruitment introduced by the HSE is also having serious implications for the staffing of multidisciplinary mental health teams.
The pace of the implementation of A Vision for Changehas already received heavy criticism from patient groups, doctors, psychiatrists and health professionals.
In particular, the State's mental health watchdog, the Mental Health Commission, has expressed concern that key parts of the plan are not in place, almost two years after it was adopted as official Government policy.