Fear: Michael Brennan (above), whose trial for attempted murder involved a 'constant threat of intimidation'

Gardaí have initiated a total of 60 prosecutions for witness or juror intimidation over the course of the past two-and-a-half years, according to new figures.

Information released by justice minister Dermot Ahern reveals that there has been a significant jump in the number of prosecutions for these type of offences since 2008.

This suggests that witness or juror intimidation is becoming an increasing problem for prosecuting gardaí.

The figures show that during 2008, gardaí launched a total of 17 prosecutions under Section 41 of the Criminal Justice Act, which relates to witness or juror intimidation.

But by last year, this had almost doubled to 28, while within the first six months of this year, there have been a total of 15 such prosecutions. These figures are provisional and could be subject to change.

The data, released by Ahern in a written Dáil reply last week, prompted him to warn that instances of intimidation of jurors are less likely to come to notice than instances of witness intimidation. He also noted that the recent Criminal Justice (Amendment) Act had introduced significant increases in the penalty following conviction for jury intimidation of up to 10-15 years' imprisonment and/or an unlimited fine.

"The statutory provisions available to counteract jury intimidation reflect the gravity of the offence," he said."The gardaí rigorously enforce these provisions and, of course, will continue to do so."

Just last month, Dublin Children's Court heard how a teenager who had threatened to stab another teenager to scare him from giving evidence against him had pleaded guilty to witness intimidation.

The 17-year-old was subsequently given a five-year sentence for attempted robbery of the 18-year-old. Gardaí told the court that in the run-up to a hearing, the teenager approached the victim on two successive days and "made threats to stab the witness in a Circuit Court case if the allegations were not withdrawn".

Earlier this year, the Central Criminal Court also heard how the trial of a north Dublin man for attempted murder over a €200 drug debt had been conducted in an "atmosphere of intimidation".

At the sentencing of 22-year-old Michael Brennan, of Cromcastle Drive, Kilmore, Coolock, Judge Paul Carney praised the bravery of jury members and witnesses in the trial, after gardaí told the court that from the start of the investigation there had been "a constant threat of intimidation".

Brennan was convicted by a jury of the attempted murder of James Egan and of possession of a sawn-off shotgun with intent to danger life. He was sentenced to eight years in prison for the firearms offence, to run concurrently with his 10-year sentence.

Under Section 41 of the Criminal Justice Act, it is an offence to harm or threaten or in any other way intimidate, or put in fear another person who is assisting in the investigation of an offence, or who is a witness or potential witness or a juror or potential juror in proceedings for an offence.

It is also an offence to do this to a member of the individual's family, "with the intention of causing the investigation or the course of justice to be obstructed, perverted or interfered with".