Greece's left-wing government, elected in January, is releasing detainees from immigration centres and allowing them to move freely around the country.

The government says they were being held in horrendous conditions, and their continued incarceration is unaffordable.

(Transcript from World News Radio - click on audio tab to listen to this item)

Like other European countries on the Mediterranean, Greece has seen a huge increase in the number of people trying to enter the EU in boats from Africa.

Many also enter Greece on land via its porous eastern borderlands.

Those detected by Greek authorities are usually locked up in one of seven detention centres.

In all, around 3,500 people are in detention, including children.

Greece has already faced a one million euro fine from the E-U over the squalid state of those centres, and the government has now taken the step of releasing people into communities.

Greece's immigration minister Tasia Christodoulopoulou says it was not just the EU fine that prompted the mass release.

"The people that were there, were living an indescribable barbarity," she said.

"The centres did not meet basic needs, and moreover most of those that were being held were being held illegally."

The government has not set up any alternative provision for the people once they're released.

But Ms Christodoulopoulou argues the government has little choice because holding them for indefinite periods is illegal.

"It's true the infrastructure does not exist but it's not the fault of those being held, and nor can they face this agony for the rest of their lives," she said.

Greece's economic woes are well-chronicled.

The debt crisis smashed the nation's finances and left scant funds in the budget to tackle immigration issues.

Greece initially turned to the EU for funding, but that stream has now dried up.

Greek immigration officials are now seeking abandoned hotels and state residential buildings to house the former detainees.

Many have nowhere to go once they are released and gather in city squares with their belongings.

Pakistani migrant Ramzan Nazeer Ahmet was held in the Amygdaleza detention centre outside Athens before his recent release.

Like many others, he doesn't have the proper documentation to find a job.

The 25-year-old says conditions in the detention centre are deplorable, the rooms would flood and the food is inadequate.

"This was like a prison, this was not a centre, at centres you can go outside, you can play ball, this was like a prison," he said.

"Each room had four people in it and the door was locked."

Ramzan Ahmet also alleges he was beaten by guards.

"I just want a decent life," he said.

"If police said I had to stay in there for 18 months then that was fine, if police said I had to stay for two years that was fine, but no one said anything about being beaten up.

"I don't like to be beaten, I don't want free food if you have to get beaten up."

The former conservative government of Antonis Samaras launched a sweep operation in 2012, arresting thousands of undocumented immigrants and sending them to detention centres.

In the last few years the situation has aided the extreme far-right in Greece to rise to third in the most recent general elections.

Residents in Athens and other cities, fearing crime and disease, have complained about uncontrolled migrant ghettos forming in neighbourhoods.

The United Nations Human Rights High Commissioner's European representative Jan Jarab has met Greek officials during a visit to Athens at the end of March and toured the Amygdaleza detention camp.

He says the UN supports the government's moves to release the migrants but demanded it be coupled with an assistance program.

"It is not just to replace detention by destitution, by leaving persons destitute in the streets," he said.

"There has to be facilities of a non-prison type character and it is clear that to create all this will require a kind of redirection of government's energies, redirection of government financing. So, we are ready to accompany the Greek government in this process."