Greece will open the first of up to 30 camps for illegal immigrants within weeks, in what some describe as a "desperate bid" to contain the social chaos prompted by the economic crisis.

In Athens officials have approved the construction of three of the 30 detention centres that the government has vowed to build on disused military sites.

"The first centre will begin operating in the next 30 to 45 days," the deputy public order minister, Manolis Othona, said. "It will open as long as the buildings are in sufficiently good shape."

It was the first official confirmation that the camps would be operational before the Greek general election in early May.

A wave of migrants from the developing world has been blamed for a rise in crime that authorities say has assumed "epidemic proportions".

Break-ins, robberies, muggings and murders have soared, with burglaries rising by 125% in the greater Athens region in 2011, according to Greek police.

"On the basis of arrests and investigations we believe that up to 70% of violent crime is perpetrated by foreigners and I say this without wishing to demonise migrants," said police spokesman Thanassis Kokkalakis.

"Unfortunately, the influx has increased with a 20% rise in the number of Africans and south-east Asians noted across the Greek-Turkish border since the start of 2012."

Migrants' groups and leftist parties have both criticised the camps as degrading and resonant of the worst excesses of Nazi rule. "It's not the migrants who are responsible for rising crime, but policies that Greece is being forced to take [by the EU and IMF] that are spreading poverty, unemployment and misery," said Petros Constantinou, national co-ordinator of the movement against racism.

For several consecutive years more than 90% of all illegal migrants detained in the EU have been caught in Greece. Around 130,000 are estimated to enter the country each year, exploiting the long, unwieldy Greek coastline and the porous northern frontier which would-be migrants view as Europe's back door.

Many migrants survive in appalling conditions in the heart of Athens, transforming parts of the historic centre into a dangerous and insanitary ghetto.

"Everyone is afraid. Athens has become a city of fear," said Dr Nikitas Kanakis, who heads the Greek branch of Doctors of the World, which works with the migrants. "The lack of night shelters or public places to go and wash is a huge problem."

Around 5,000 migrants have been revealed as living in an estimated 500 abandoned buildings. More than 2,000 other properties occupied by migrants have been denounced as unfit for human habitation. Doctors and officials have described the conditions as a "public health time bomb".

Police with sniffer dogs conducted a major "sweep" of the area on Thursday, rounding up undocumented migrants and illegal street vendors.

"The current situation cannot continue," said the citizens' protection minister, Michalis Chrysohoidis, announcing the campaign to move 30,000 illegal migrants into "closed hospitality centres" under a €250m (£208m) EU-funded scheme.

"Hundreds of thousands of people are wandering aimlessly through the streets, being forced to break the law, being exploited by criminal networks and deterring legitimate immigrants from staying in the country."

Under the programme migrants would be "given hospitality" in the centres before being "immediately asked to return home", Chrysohoidis added.

The move has been welcomed by residents and business owners in central Athens where streets fights regularly erupt between gangs and migrants.

Mired in its fifth straight year of recession, Greece's jobless rate has reached a record 21% with youth unemployment now at an unprecedented 51%.

"They will call us racists for doing this but the situation is clearly out of control," said Vangelis Kontopoulos, who helps run a cafe within view of the Acropolis.

"A lot say it would be better if we issued green cards that allowed them to move on to other countries in the European Union but that's never going to happen. EU law has seen to it that they can't move on. They're trapped here."

The Athens mayor, Yiorgos Kaminis, told the Guardian he welcomed the measures but cautioned that they would only work if there was "full respect of human rights, including the right to asylum".

He added: "We also have to step up the fight against illegal migrants and promote the fight for the faster absorption into society of legal migrants."

Chrysohoidis insists the detention centres will help the local economies they are located in, by creating thousands of jobs, from cleaners to private security guards who, alongside armed police, will patrol the sites, which will include former barracks and airfields.

But regional prefectures across Greece remain sceptical about the camps, with many local officials voicing concerns over the dysfunctional Greek state's ability to create problem-free facilities. The detainees will far outnumber Greece's jail population, which currently stands at 12,500.

With a neo-fascist right rising in popularity amid the migrant influx, a growing number of immigrants would prefer to be repatriated. "There's a lot of tension between the different ethnic groups and I'd say 90% of the new arrivals want to leave Greece but don't have the means," said Azad Kerim, a Kurdish migrant.

"It's much better in Iraq than it is here. More and more are discovering they've made the journey for nothing," he said, adding he had waited 15 years to acquire the papers that would give him legal status in Greece.