Former Fianna Fáil junior minister and senator Ivor Callely has been granted permission by the High Court to challenge the refusal of the Minister for Justice to grant him temporary release or enhanced remission from his prison sentence.

Callely is serving a five-month sentence for fraudulently claiming mobile phone expenses while he was a senator.

He is in Wheatfield Prison, where the court was told, he has been working in the prison grounds every day since 12 August.

His lawyers told the court he is being treated unfairly because of his high profile as a former politician.

A letter was read to the court in which Minister for Justice Frances Fitzgerald refused to grant him temporary release because she said his breach of trust and abuse of public funds must be considered in such serious terms that she found he was not eligible for temporary release at this stage of his sentence.

Callely says he has not received any response to his application for enhanced remission of a third of his sentence, and he says that is tantamount to a refusal.

If his application for enhanced remission was accepted, he would be due for release today, the court heard.

Callely says the reasons given by the minister for refusing his release are extraneous and he is being punished on the double.

He says he was given a prison sentence because of his high profile and now he is being refused release also because of that profile.

Callely says her decision flies in the face of common sense.

Callely has been in Wheatfield Prison since 1 August after being moved from Mountjoy Prison.

There were concerns for his welfare at first, the court heard, and he was in 23-hour lockdown until 12 August.

Since then, he has been working on the prison grounds.

The court was told he has been an exemplary prisoner and deserves enhanced remission.

Barrister Kieran Kelly said that from an early juncture in his imprisonment, Callely had meetings with the prison governors and chiefs.

He says they consistently and continually told him that if he was the "normal" type of prisoner, he would have been released by now.

He said Callely had committed a non-violent offence and had no previous convictions.

Callely claims a number of prison governors personally told him it was "not right" that he was still in prison.

He says one governor told him if he received early release it would get media attention, and that would be unpalatable for those at a higher level.

Callely said a former councillor "from the minister's own party", believed to be former Fine Gael councillor, Fred Forsey, was granted temporary release recently.

He claims he is being unfairly treated.

He said he was a member of Fianna Fáil and challenged the decision of an Oireachtas committee of which Ms Fitzgerald had been a member.

Mr Kelly said Callely believes the minister does not want to be seen to favour politicians, but he said people convicted of armed robbery or drugs offences routinely receive temporary release.

Ms Justice Mary Faherty granted him permission to challenge the decision.

The matter will be back before the High Court next Tuesday.