Former priest and serial child abuser Tony Walsh has failed in appeals against separate sentences of 16 years and 15 months imposed on him.

The jail terms were handed down for what the Court of Criminal Appeal has described as the "depraved" rape and sexual abuse of young boys in the 1970s and 80s.

Walsh, who was known as the "Singing Priest" for his role in a travelling all-priest vocal group before he was defrocked, is serving a 16-year sentence imposed on him in 2010 for the rape and abuse of three schoolboys.

In 2012 Walsh had 15 months added to this sentence for abusing two other boys.

In a written judgment delivered today by presiding judge Mr Justice John Murray, the appeal court said that with regard to the first appeal the offences were of the "utmost gravity".

He said even that description did not do justice to the "appalling nature" of the offences committed against young boys.

The effects these "appalling crimes" had on the victims was severely and permanently damaging to them as persons and in their capacity to ever again lead fully normal lives, the court said.

"In short, as regards these offences, his [Walsh's] conduct over a period of four years in serially abusing the boys concerned must be characterised as nothing less than depraved," the court said.

With regard to the second appeal, the court noted that Walsh had "used and abused his position of spiritual trust" as a priest to assault the young boys who "suffered a grave injustice at a young age".

Walsh, 60, had pleaded guilty at Dublin Circuit Criminal Court to two counts of indecently assaulting a male in a west Dublin church between November 1978 and April 1979.

He pleaded guilty to a further charge of indecently assaulting a male in a west Dublin school between January 1984 and December 1985.

He was convicted by a jury in November 2010 of a further nine counts of indecent assault and five counts of buggery on the third boy between 1 June 1979 and 30 June 1983. He had denied the charges.

There was evidence that Walsh became a curate in the area in 1978. He met the first victim when the child was seven years old.

He later invited him to his home to listen to his record collection.

He would put the boy on his knee and molest him, sometimes giving him sweets afterwards.

The boy would visit him twice a week for five years and the abuse would occur on most occasions.

One day after a sports event he tied the boy up with ropes from his vestments and raped him, turning up the music when the boy's cries got too loud.

After this, rape would occur regularly during these visits.

In 2012 Walsh, formerly of North Circular Road, Dublin, pleaded guilty at Dublin Circuit Criminal Court to two counts of indecent assault on 1 January and 4 April 1979.

The victims were aged between ten and 11.

With regard to these offences trial judge Martin Nolan said that Walsh had worked his way into the confidence of the families of the two victims with "coldblooded intent".

He said the sexual assaults were aggressive and incredibly frightening and violent for the children involved.

In 1997 Walsh was convicted of abusing six victims and sentenced to ten years in prison. This was later reduced to six years on appeal.

Mr Justice Murray today said that in each application brought by Walsh the court would refuse leave to appeal.

On the first application Mr Justice Murray said the court found the grounds put forward were not sustained and were not a basis for impugning the decision of judge Frank O'Donnell, who exercised his discretion in accordance with the general principles of sentencing and made no error in principle.

As regards the second application, the court found that the trial judge had a range of options open to him because of the previous grave offences of which Walsh had been convicted. 

Mr Justice Murray said the court found that Judge Nolan acted within his discretion when he made the 15-month sentence consecutive.

It may well have been open to the judge to impose a concurrent rather than consecutive sentence, Mr Justice Murray said, but it was not for the court to decide what sentence it felt appropriate to impose but rather if the trial judge erred in principle.

He said the court found the trial judge acted within the ambit of his discretion and accordingly would refuse the appeal.

Counsel for Walsh, Remy Farrell SC, had told the court that he had not set out to make it an issue of guilt or innocence by the back door and argued for a reduction in his client's sentences.

He said a comment by the then sentencing judge that Walsh had fought his case tooth and nail gave rise to an error.

Referring to case law, counsel said it seemed to penalise somebody for exercising their right not to plead guilty.

Mr Farrell also asked the court to consider an appropriate sentence in respect of an offence that no longer existed, that being the offence of buggery.

Counsel for the DPP, Mary Rose Gearty SC, said Walsh had engaged in a long campaign of offending from the 70s right up to the 80s.

She said Walsh was sentenced for abusing two new complainants and that each of his convictions involved a separate tranche of victims.

Therefore, she said, it could not be argued that his sentences were cumulative as had been argued by Mr Farrell.