A DNA database to help crack down on serious and violent crime has been held back amid concerns over what samples can actually be held by gardaí.

The Department of Justice has confirmed that it has been forced to temporarily delay legislation after a European Court of Human Rights judgment, which curtails the government's right to retain DNA samples.

In the case, two British men successfully challenged the right of UK police to hold on to their genetic profile and fingerprints.

Neither of the men had been convicted of any offence and the judgment said retention "could not be regarded as necessary in a democratic society".

The Department of Justice said that the judgment had caused a delay to Irish plans for a database.

A statement said: "The timetable for publication [of the bill] has been affected somewhat by the need to consider and take account of the implications of the judgment of the European Court of Human Rights in the case of S and Marper v the United Kingdom.

Gardaí believe the judgment means the planned Irish database will now be much more limited than previously hoped. It could mean they will be obliged to destroy all fingerprint and DNA samples if they cannot secure a conviction in court.

The chances of 'accidental hits' will become almost impossible and some recent garda successes would no longer even be possible under the new system.

In one recent case, gardaí successfully matched DNA data after 20 years from a missing woman to a former army sergeant John Crerar.

It was key evidence in finding him guilty of murder but under the European Court judgment, the state would have had no right to hold on to his DNA sample if he had not been charged with an offence.

Gardaí now believe the possibility of actually having an effective databank is unlikely and believe the number of samples involved may never number more than a few thousand.

Large-scale trawling for DNA evidence in cases of rape or murder will also be of limited value because of the number of samples involved.

The European ruling involved two English men: Michael Marper was arrested in 2001 on suspicion of harassing his partner but the case was subsequently dropped, and he had no previous convictions. A second man – a teenager identified only as S – had been arrested and charged with attempted robbery but was acquitted.

In both cases, police refused to destroy fingerprints and DNA samples taken when the men were first arrested.

Their case was originally thrown out by the House of Lords but when taken to the European Court of Human Rights, it proved successful.