Director of Public Prosecutions Claire Loftus has warned the media and commentators about interfering with an accused person's right to a fair trial.

In the foreword to the DPP's 2012 annual report, Ms Loftus said trials risked being postponed for a long period or even indefinitely because of prejudicial material.

She said: "I want to take this opportunity to say something generally about the risks of pre-trial publicity interfering with the right of an accused person to a fair trial.

"The media and commentators have a high degree of responsibility to ensure that not only do they not commit a contempt of court by publishing or broadcasting prejudicial material but also that such publicity is not the cause of a trial being postponed for a long period, or even indefinitely.

"These risks increase as any trial date approaches."

Elsewhere, she said she was concerned at the backlog of Court of Criminal Appeal cases, and the impact this was having on delays hearing leniency and other types of appeal.

Noting the referendum on a Court of Appeal next month, she said the longer term problem of delays, both at Court of Criminal Appeal level and at Supreme Court level, would hopefully be addressed.

Meanwhile, the number of prosecution files submitted to the office in 2012 was down on the previous year to just over 15,000.

However, Ms Loftus said although the number of files relating to more serious offence categories was also down, these type of cases continue to increase in complexity and size.

The cost of running the service rose by more than €2m to €38.8m.

Although fees paid to counsel were down more than 9%, costs awarded against the office rose 95% in 2012 to more than €5m.

Since the 2008 decision to change the policy in relation to reviewing decisions made in cases, 41 requests have been received and the majority of these (66%) related to fatal road traffic offences.

Detailed reasons were given In 35 cases, three requests were declined, two are pending and one was withdrawn.

The number of applications to review sentences on the grounds of undue leniency halved between 2011 and 2012 to 21.

But the office continues to receive an increasing amount of requests for mutual assistance from overseas authorities.

The report said 223 requests were received in 2012, almost three times the number of requests received in 2010.