The Health Service Executive has said it will continue to pay the medical expenses of those suffering from a sleep disorder claimed to be linked to the human swine flu vaccine.

It follows a letter that was sent out to families last month saying the payments were to stop.

HSE Director General Tony O'Brien has said he was unaware of the letter until this morning and said that it will be set aside.

Up to 60 children and a number of adults were diagnosed with narcolepsy after taking Pandemrix in 2009 and 2010.

Meanwhile, lawyers for two families told the High Court they have today received legal correspondence on behalf of State agencies, which appears to confirm the reinstatement of all entitlements.

The families had been told that reimbursement of their medical expenses for children with narcolepsy would cease if they sued the State.

Michael Cush, SC, told Mr Justice Michael Peart that his clients wished to seek further clarification on the letter received.

Leave to re-enter the legal challenge was granted.

Mr O'Brien today said he would not countenance any discrimination, either perceived or real, against any person asserting their legal rights.

He also apologised to anyone who had been caused distress by the letter.

The letter dated 20 November was sent by Greg Price, the Director of the HSE's Advocacy Unit. 

The correspondence, which was seen by RTÉ News, said the HSE had based its decision on the direction of the State Claims Agency.

The HSE this evening issued a statement apologising for any distress or upset caused by the letters.

It said: "In writing to suffers of narcolepsy, it was never the intention of the HSE to withdraw any discretionary medical cards or any other health services or supports.

"The letter that issued by the HSE never stated that the State Claims Agency advised the HSE of any requirement to alter its approach in this regard.

"The interpretation of the letter by some media may have given an impression that the HSE had intended to withdraw such medical support."

The HSE said the Director General "wishes to make it absolutely clear that he has given a direction that medical supports and services will not be withdrawn for this category of narcolepsy sufferers".

It added that he "wishes to apologise if the letter issued has caused any distress or upset to any person, family or group".

Pandemrix was made by pharmaceutical firm GlaxoSmithKline and was fast-tracked for use due to the human swine flu crisis.

The State gave the makers of it an indemnity.

Following a vaccination programme in Ireland in 2009 and 2010, around 60 children were diagnosed with the narcolepsy sleeping disorder.

Until now, the State has provided those affected with discretionary medical cards and also covers the cost of scans and private consultant visits.

A report for the Department of Health, published last year, found that the risk of narcolepsy was 13 times higher among those given the vaccine, compared to unvaccinated individuals.

Meanwhile, Director of Quality and Patient Safety at the HSE Dr Philip Crowley said the executive is fully responsible for the care of those who take legal action against the State over sleeping disorder problems they claim are linked to Pandemrix.

Speaking on RTÉ's News at One, Dr Crowley apologised for anxiety caused to those who received the letter and reiterated that the HSE will continue to fund all medical care that they need.

The State Claims Agency has said it did not advise the HSE of any requirement to alter its approach to the awarding of items such as medical cards or the provision of other normal benefits and supports for those affected by narcolepsy.

In a statement, the SCA said that it informed the HSE to cease making ongoing out-of-pocket payments to individuals who were suing the State and that these individuals should include these expenses as part of any special damages claim.