Senior assistant director Stephen Herron told BBC News: “The PPS director is on the record about the impact that such allegations from politicians can have on the public confidence in the service.

“I’m heartened by the fact that in the last Northern Ireland Omnibus survey around 70 per cent of the public surveyed feel that we did take decisions in a fair and impartial manner.”

It comes as senior UK politicians accuse the Director of Public Prosecutions, Barra McGrory QC, of prioritising prosecutions of former British soldiers for their actions during the Troubles.

In one sensational attack, Sir Gerald Howarth, MP for Aldershot, used parliamentary privilege to label him “the Sinn Féin-supporting Director of Public Prosecutions for Northern Ireland”.

Mr Herron also spoke to the BBC about changes over the past decade, including the fact that the PPS now works with the Police Service of Northern Ireland (PSNI) to build cases at a much earlier stage.

He said: “This is to ensure that cases at the outset are looked at strategically, so they are put together in a way that they can withstand robust cross-examination by the defence.

“We also have to make sure we’re not building a case where we get a conviction at any cost.”

Mr Herron also said delays in cases needed to be addressed not only be legislative reform, but also “somewhat of a cultural change as well”.

He said: “We have to get used to the fact that we cannot continue to have the same level of resource either from the police or prosecutors put into every type of case.”

Mr Herron said he would like to see a more proportionate approach to lower-level offending, with “a caution or informed warning” offered in some cases even where the test for prosecution has been met.

He said: “There has to be another way that cases are listed in court so that we have fewer and more effective hearings and a lot of that involves us getting it right first time.”