Lawyers representing the Department of Education and the State have written to people who were sexually abused in schools as children warning them to withdraw legal cases against it or potentially face significant costs.

The letters cite recent High Court judgments which found that a European Court of Human Rights ruling of State liability in the Louise O'Keeffe case was not applicable in other actions currently before the courts.

The letters say the State parties are prepared to bear their own costs in proceedings to date, but only on the strict condition that the cases are withdrawn within 21 days.

Ms O’Keeffe, a survivor of child sexual abuse, lost her case against the State in the Irish courts in 2009.

Afterwards, the State wrote to other survivors warning them to withdraw their legal actions or be pursued for costs should they lose.

After this warning the majority abandoned their cases.

However Ms O'Keeffe went on to be vindicated by the European Court of Human Rights.

Two years ago it found that the State was liable for what she had suffered in school and that ruling encouraged others to once again pursue cases against the State.

But the High Court has recently ruled against some of them, saying that the Strasbourg judgment, although binding on Ireland, is not applicable in the High Court.

The State has now written again, however this time the warning is not explicit but it is implied. The letter states that if cases are withdrawn within 21 days then the State will bear its own costs.

Otherwise, it says, the State parties reserve their right "in full" to seek to "bring finality" to the matter.

Ms O'Keeffe told RTÉ News that the State was doing "the exact same thing again".

"It is obviously implied", she said, "that if you don't withdraw your case then we will come after you for costs".

Two years ago, responding to the European Court ruling, the Department of Education said in a statement that the abuse Ms O'Keeffe and others were subjected to was "a source of national shame".

The statement said "it has taught us lessons that we as a country must never forget".

Minister for Education Richard Bruton has said the State had tried to improve protection for people and deal with them in as humane a way as possible.

Mr Bruton said there were cases recently which had rejected by the High Court and the courts and legal process had to be respected.

He said the State was offering an opportunity to bring these matters to a close so there would not be costs borne by people pursuing such cases.

Mr Bruton said he will keep a "close eye on these developments".

He said the State provides an ex-gratia payment so people do not have to go through a complicated legal process if they fall under the terms of reference in a redress scheme.

When asked about those who do not fall under the terms of reference, the Minister said the courts have to decide where liability falls.

Speaking on RTE’s News at One, Ms O'Keeffe said the letters are not surprising.

She said she would have hoped the department and the State would have learned their lesson in not sending out such letters and said the action is disheartening.

Ms O'Keeffe said the department failed to protect children and the European Court of Human Rights ruled the State neglected its duties.

She said the letters are intimidating and believes settlements should be made to people who have cases pending and to people who discontinued their cases under the threat of similar letters from the State.