Dr Toben has previously called the Holocaust "a lie"on his website
An Australian wanted in Germany for alleged Holocaust denial should not be extradited because he has committed no crime under UK law, a court has heard.
Dr Gerald Toben, 64, was arrested at Heathrow Airport by British police, acting on behalf of a German court.
His lawyer told the extradition hearing that Dr Toben should only be extradited if he had made his claims in Germany or had posted them on a German website.
The case was adjourned until 29 October, when a judgement is expected.
Dr Toben, also known as Frederick, was arrested and taken into custody whilst on a stopover between the US and Dubai.
Police were acting on an EU warrant that provides for "fast-track" extradition of suspects who have committed alleged offences in other European countries.
The 64-year-old historian is wanted for publishing material online "of an anti-semitic and/or revisionist nature" - a crime punishable by imprisonment in Germany, but not in the UK.
Dr Toben's material appears on his Australian-based website, which the German authorities say can be accessed in Germany.
His lawyer, Ben Watson, questioned the validity of the EU warrant and said that there was not enough information within the warrant to justify Dr Toben's extradition.
Mr Watson told the hearing in London that his client should only be extradited if he committed the offence whilst "standing in Cologne market place or had posted the claims on a German website".
But prosecutors said that there was enough information within the warrant to suggest that a full extradition hearing should take place.
Melanie Cumberland, prosecuting, said: "The conduct alleged against this defendant is clearly indicated in the application."
She added that although the offence of Holocaust denial was not specifically against the law in the UK, offenders could still be prosecuted under anti-racism laws.
Holocaust 'a lie'
Dr Toben, born in Germany but now a naturalised Australian citizen, has in the past described the Holocaust as "a lie".
His Australian-based website, the Adelaide Institute, has carried the transcript of an interview in which Dr Toben says there is "no proof" that Hitler systematically exterminated the Jews. He also described Auschwitz as a "transit camp".
In court, Dr Toben's lawyers said the former schoolteacher "never sought to cause offence by his work".
Mr Watson told the City of Westminster Magistrates Court: "He's not right wing or a nationalist."
District Judge Daphne Wickham remanded Toben in custody until a further hearing on 29 October when she will give her judgment on whether the case should be thrown out.