Michael Fassbender in the film 'Hunger' portrays Bobby Sands during his dirty protest

A dirty protest at Portlaoise prison enters its 25th day today, with prison officers saying they see no signs that the six Real IRA inmates involved will soon end their demonstration.

The prisoners began their protests because periods of temporary release had been withdrawn by justice minister Dermot Ahern following the Real IRA murders of two British soldiers outside a barracks in Co Antrim in March.

"This is like a throwback to what we were dealing with 25 years ago. This could get a whole lot worse before it gets better," said a prison source. "[These are] horrendous working conditions. We'd like a lot more support from the Department of Justice on this. We'd like them to recognise we have a serious problem."

None of the six inmates involved are high-profile Real IRA members and the protest is confined to the E3 landing at the moment.

"They are the ones doing it; there's very little we can do to stop them. They have to make that decision themselves," said another prison source.

"There's been talk of others joining in too but at the moment it's still the six of them. These things happen in prisons from time to time but with these guys, because they're quite militant, we don't know when it will end and there's no sign of it happening at the moment. They have been spoken to about it."

It emerged last week that republican prisoners in Portlaoise maximum-security jail enjoy a relatively relaxed regime in which they hold military-style parades and have murals on the walls.

The six inmates' cells have been cleaned just once since they began their protest.

"They're saying they won't stop until the minister gives in to their demand," the source added. "People have been saying it's a relaxed regime at Portlaoise and that's unfair. It is a different type of prison that holds a certain category of prisoner."

Meanwhile, the blanket blocking of mobile phones is being phased in at Portlaoise prison and is expected to be completed by the end of the month.

The introduction of new 'blocking' technology has upset prisoners but is not linked to the on-going dirty protest.

Following the introduction of the technology at Portlaoise, which is being introduced in stages across each landing, it will be rolled out at Dublin's Cloverhill prison before being implemented across all the prisons.