A Northern Irish dissident Republican has failed in her attempt to overturn a conviction for attempting to murder police officers with a pipe bomb and has instead had her prison sentence increased to 25 years. 

Christine Connor, 35, was convicted of attempted murder and causing an explosion likely to endanger life last year in relation to a series of pipe bomb attacks in Belfast on May 16 and May 28, 2013. 

She was initially handed a 20-year prison term by a judge in a non-jury trial but appealed against her convictions and the length of the prison sentence in Northern Ireland's Court of Appeal. 

However, Northern Ireland's Director of Public Prosecutions also appealed Connor's prison sentence, arguing that it was unduly leniant. 

Connor's appeals were dismissed by three Court of Appeal judges, who upheld the Director of Public Prosecutions Appeal and increased her sentence from 20 years to 25. 

Connor's legal team had argued that there was no evidence of a device likely to endanger life or damage property in the area during the May 16 incident, suggesting that the explosions had been caused by fireworks. 

However, the original trial judge dismissed the suggestion and said that he was satisfied beyond all reasonable doub that the explosions were caused by pipe bombs. 

The Court of Appeal judges upheld the trial judge's findings, stating that there was "no discernable flaw in his approach". 

"The undisputed evidence was that pipe bombs are constructed with the aim of showering shrapnel in all directions," Lord Justice McCloskey said while delivering the judgement. 

"We consider that there was ample evidence to support the judge's finding that the devices were pipe bombs and that, in those circumstances and in light of the other evidence before him, they were likely to endanger life or cause serious injury to property.

Connor contended that there was no evidence of an attempt to kill a police officer during the second attack on May 28, claiming that she hadn't thrown the pipe bomb and couldn't be convicted of attempted murder as a result. 

However, the Court of Appeal ruled that it was not necessary to prove whether she had thrown the bomb or not given that she was involved in the terrorist plot. 

The three judges said that the trial judge's approach was beyond criticism. 

"He engaged with the defence arguments, he took into account all material aspects of the evidence, he left nothing material out of account and he reached an outcome which was reasonably available to him," McCloskey said. 

However, the judges found that the trial judge had been "unsustainably generous by handing down a 20-year prison term and increased her sentence to 25 years. 

The trial judge indicated three mitigating factors when delivering the prison sentence last year, including the defendant's mental and physical health, the poor quality of the pipe bomb, and the defendant's limited criminal record. 

The judges, however, argued that an attempt to murder Northern Irish security services was a heinous crime that warranted a condign punishment. 

Connor will be subject to a further four years on license in addition to her 25-year prison term.