In an interview published in the Rheinische Post, the minister, Hans-Peter Friedrich, said there was a core of about 1000 extremely violent neo-Nazis who could not be easily monitored.
Meanwhile, the anti-fascist magazine Searchlight revealed that Breivik had been in contact with the EDL and its Norwegian counterpart, the Norwegian Defence League.
Searchlight claimed that for internet communications, Breivik used the pseudonym Sigurd Jorsalfare after a Norwegian king who led a Crusade in the 12th century.
He was also reported to have met a group called Knights of the Templar Europe in London during 2002 and his approval for Britain's far right was stated in a posting on an EDL website on March 9 this year.
"Sigurd" wrote: "Hello. To you all good English men and women, just wanted to say that you're a blessing to all in Europe, in these dark times all of Europe are looking to you in such [sic] of inspiration, courage and even hope that we might turn this evil trend with islamisation all across our continent ..."
The EDL has condemned the Norway attacks and denied any official contact with Breivik, but one of its leaders warned on British television that similar atrocities could occur in Britain if the right of protest was taken away.
Stephen Lennon told BBC2's Newsnight: "You need to listen because, God forbid, you're probably five or 10 years away."
The EDL insists it is a peaceful protest group which opposes militant Islam but since its inception in 2009 violence has erupted at most league demonstrations in Britain. Weapons have been seized and city centres brought to a standstill.
While Lennon - who was convicted this week of leading a street brawl involving 100 soccer fans in the English city of Luton in August last year - is the public face of the EDL, a millionaire Briton called Alan Lake is one of the strategists behind it.
A computer expert who shuns publicity and runs a website called Four Freedoms, Lake's aim in his own crusade against Islam has been to unite "thinkers" and "those prepared to take to the streets".
In reference to Breivik's crimes, Lake wrote on his website: "He did this attack to protest against the way that Islam is taking over large parts of Europe. By attacking the leftist politicians that are enabling this, the chickens have come home to roost."
Lake rarely talks to the press, but when we met in London in 2009 he said that for years he had been in contact with similarly minded individuals in various countries around the world including Australia, Sweden, Belgium, Holland, France, Germany, USA and Israel.
He spoke of his admiration for Russia's nationalists and the far-right Freedom Party (FPO) in Austria which has been highly successful in garnering public support through its virulent anti-Islam stance.
The FPO - viewed as a model of excellence for extreme far-right parties across Europe - and the Alliance for the Future (BZO) jointly secured almost one third of the vote during Austria's 2008 election. Drumming up hatred of foreigners and campaigning against the "Islamisation" of Austria, the two parties secured 29 per cent public support. Both parties ran xenophobic campaigns, particularly the FPO, which pledged to set up a ministry to deport foreigners.
More sinisterly, the FPO wants to revoke the Verbotsgesetz, an Austrian law enacted in 1947 that bans the promotion of neo-Nazi ideology.
FPO leader Heinz Christian Strache - the youthful, handsome star of Austrian politics - was photographed wearing army fatigues and clutching what appeared to be a gun in a forest.
The images were allegedly taken at a neo-Nazi training camp in his youth but Strache said they were from a day out paint-balling.
He was also photographed apparently giving a three-fingered neo-Nazi salute in a bar, but said he was ordering three beers.
The FPO has tried to distance itself from extremism but the party was founded by two former SS officers, Anton Reinthaller and Herbert Schweiger.
In 2008, I interviewed Schweiger - who died this month - at his home in Austria a few weeks before he was due in court - for the fifth time - charged with promoting neo-Nazi ideology.
Described to me as the "puppet master" of Austria and Germany's far right, Schweiger, 85, was remarkably sharp-minded and spoke proudly of his Nazi views.
He was a lieutenant in the Waffen SS Panzer Division Leibstandarte Adolf Hitler, an elite unit formed in the 1930s to act as the Fuhrer's personal bodyguards.
After escaping a prisoner of war camp during World War II, Schweiger returned to his homeland, Austria, where he lived openly from 1947 and became heavily involved in politics.
He also admitted involvement in terrorism and training a far-right cell comprising Burschenschaften (right-wing brotherhoods founded in universities) who were fighting for the reunification of Austria and South Tyrol, now part of Italy, in 1961.
Thirty people in Italy were murdered during a bombing campaign.
Schweiger said that - despite his age - he still travelled widely in Austria and Germany to teach "the fundamentals of Nazism" to underground cells of neo-Nazis who, he claimed, had infiltrated mainstream political parties such as the FPO.
The FPO disputes this, but Vienna's Documentation Centre of Austrian Resistance, which monitors neo-Nazi activity, says it has strong links to extremism, particularly through the Burschenschaften.
Drawing two circles on a piece of paper, researcher Heribert Schiedel explained: "In the circle on the left you have legal parties such as the FPO. In the circle on the right you have illegal groups such as Blood and Honour. Two distinct groupings who pretend they are separate."
He drew another circle linking the two. "This circle links the legal and illegal," he said.
"This signifies the Burschenschaften, right-wing brotherhoods founded in German universities. They have long been associated with fascism and have a history of terrorism.
"Adolf Eichmann, Rudolf Hess and Heinrich Himmler were Burschenschaften - as are prominent members of the FPO in parliament."
The Burschenschaften were banned by the allies after World War II, but reformed in the 1950s.
Senior members of the FPO are Burschenschaften, including Strache and Martin Graf, who was elected the deputy president of the Austrian Parliament after the election despite vociferous opposition from concentration camp survivors.
The party continues to build support and last October it took 27 per cent of the vote in Vienna's provincial election. Later that month, it hosted a two-day conference attended by far right factions from across Europe.
As the economic crisis deepens and extremists stir up hatred of Muslims, the growing fear is that more European voters will turn to extreme far right parties.
It is still unclear whether Breivik acted alone or was part of a conspiracy but alarm bells are ringing and Europe's far right is under scrutiny.
