An English Defence League supporter gestures during a rally in Luton, Hertfordshire, in 2011. Photograph: Carl Court/AFP/Getty Images
The rally will take place a few weeks before the start of the trial of Anders Behring Breivik, the far right extremist who has confessed to the murder of 77 people in Norway last July, and is expected to attract supporters of at least 10 anti-Islamic and far right groups from across the continent.
It is the second time the EDL has tried to hold a meeting in Europe. In October 2010 about 60 supporters turned up to a planned rally in Amsterdam and were attacked by Ajax football fans and anti-fascists.
The EDL claims the 31 March event will be bigger. It is expected to attract several hundred people drawn from defence leagues and other far right groups that have emerged around Europe over the past two years.
Observers are divided over whether the event is a significant step towards a coherent European far right movement but the possibility has raised concern.
Nick Lowles from Hope not Hate, which campaigns against racism and fascism, said he was not expecting a big turnout but added some key figures from emerging far right groups would be there.
"The march in Denmark will bring together many of the leaders of the so-called 'counter-jihad movement' and it is another sign of the growing international anti-Muslim networks," he said.
The EDL says the Denmark rally will discuss the formation of a European Defence League with representatives from far right and anti-Islamic groups in Italy, Poland, Germany, Finland, Sweden and Norway expected to attend.
Lowles said: "Their focus on the threat of Islam, presenting it as a cultural war, has a far wider resonance amongst voters, especially in northern Europe, than old-style racists. They conflate Islamist extremists with immigration and in the current economic and political conditions it is extremely dangerous."
Claude Moraes, the Labour MEP for London who chairs the all-party group on racism in the European parliament, described the demonstration as a critical moment and said there was widespread complacency about the threat posed by groups such as the EDL among mainstream European politicians.
"They have missed what is a fundamental change in the way the far right is working. Despite all the evidence of the growing influence and importance of these proxy groups there is still a real complacency about how they are operating, how deeply embedded they are becoming and how they are shaping the debate," Moraes said.
Last year, a report from the thinktank Demos found a new generation of young, web-based supporters who embrace hardline nationalist and anti-immigrant groups. It concluded that far right and anti-Islamic groups were on the rise across Europe. The exception appeared to be the UK where the British National party failed to make any breakthrough last year in parliamentary and local elections.
In a separate report, Matthew Goodwin from Nottingham University and Jocelyn Evans of Salford University found that a hardcore of far right supporters in the UK appears to believe violent conflict between different ethnic, racial and religious groups is inevitable, and that it is legitimate to prepare even for armed conflict.
Breivik claimed he had contact with the EDL ahead of the attacks, adding that he had "spoken with tens of EDL members and leaders". In response to the killings, the league issued a statement condemning the Norway killings and adding that it had no contact with Breivik.
The EDL, which emerged from Luton in 2009 to become the most significant far right street movement in the UK since the National Front, claims to be a peaceful, non-racist and set up to protest against "militant Islam". Many of its demonstrations have descended into violence and Islamophobic and racist chanting, attracting known football hooligans and far right extremists.
In the last year it has staged demonstrations in communities with large Muslim populations including Bradford, Leicester and Tower Hamlets in London. However, it has been hit by divisions and internal rows and some of its supporters have been involved in smaller, but often more violent activities, such as targeting trade union meetings and anti-racist groups.
A big turnout of anti-facists from Denmark and other European countries is expected in protest at the rally in Denmark.
Projekt Antifa, a Danish coalition of anti-fascist groups, has booked coaches to take protesters from Copenhagen to Aarhus where the demonstration is being held, describing it as "the capital's biggest anti-fascist mobilisation for more than 10 years." British anti-racists are also planning to travel to the rally. Weyman Bennett from Unite Against Fascism said he would be travelling to the event with 30 supporters.