Ability West, a voluntary organisation which provides support for people with special needs, says it is very concerned about the impact industrial action by care workers will have on the provision of services for people with intellectual disabilities.

In a statement this afternoon, it said that the action being taken by care workers was likely to escalate if a dispute over pay was not resolved. Ability West says this would have a direct and negative impact on people availing of both residential and respite services.

The organisation which offers support to more than 500 people throughout Galway City and county, says it is working to ensure the provision of safe services to all those it supports.

Around 400 care workers at Brothers of Charity and Ability West services in Galway and Roscommon today embarked on industrial action, following a long running row over extended working hours payments.

The so-called "twilight payments" are given in recognition of the anti-social hours that some health care workers are rostered for duty.

The payments were introduced around ten years ago but two grades - social care workers and social care leaders - have only been in receipt of the allowances since the beginning of 2015.

In June, the Labour Relations Commission recommended that the workers receive retrospective payments for a three year period between 2012 and 2014.

It is estimated this would cost in the region of €4.1 million. Unions claim the Department of Health subsequently rowed back from the deal and say their members have no certainty about if or when the payments will be processed.

Staff are initially working strictly to contract and not undertaking any additional duties. The care workers say they plan to escalate the action in the coming weeks but that every effort will be made to minimise the impact on service users.

The Department of Health says it is engaging with the HSE to progress the issues involved. In a brief statement it said it hoped the matter will be resolved as soon as possible.

Unions have called on Minister for Health Leo Varadkar to intervene. IMPACT Assistant Secretary General Padraig Mulligan said care staff had embarked on their action as a last resort but that they were determined to see their rights vindicated and would continue their campaign as long as was necessary.