(London) Holocaust Memorial Day was observed Tuesday in memory of some 6 million people put to death by the Nazis. Most of the victims were Jewish, but an unknown number of gays, Roma or Gypsies, Communists and dissidents were also murdered.

Under Paragraph 175 of the German penal code which banned sexual intimacy between members of the same gender, an untold number of gays and lesbians were rounded up by the Nazis and sent to concentration camps where they were subjected to medical experiments including lobotomies, and forced to work in labor camps.

Estimates of gays and lesbians persecuted by the Nazis range from several thousand to a quarter million. A large number of those interred were sent on to the gas chambers.

“The murder of six million Jews and countless Roma, Poles and other Eastern Europeans, gay men and lesbians, trade unionists, disabled people and political and religious opponents of the Nazis was not a sudden and frenzied explosion of hate, but a horror that had been methodically and carefully planned,” said British Prime Minister Gordon Brown in a statement Tuesday.

“Hatred may begin with small acts of prejudice or bigotry – but it rarely ends with them. That is why we all have an obligation to stand up to hatred.”

Monuments to gays murdered during the Holocaust are in Berlin Copenhagen and Amsterdam in Europe, San Francisco and Sydney. A monument is planned in Tel Aviv, Israel.

In Jerusalem, the Yad Vashem Museum on the Holocaust features a small exhibit dedicated to gay and lesbian victims of the Nazis.

The American Holocaust Museum in Washington also has an exhibit dedicated to gays and lesbians.

Yet there remain Holocaust deniers.

Four years ago, the United Nations designated Jan. 27 International Holocaust Remembrance Day in part to counteract “Holocaust deniers” like Iran’s President Mahmoud Ahmadinejad.

In 2003, Minnesota state Rep. Arlon Lindner (R) during debate on two bills he had brought forward to repeal gay rights laws in the state, said gays were lying when they cited thousands of homosexuals who were exterminated or sent to concentration camps by the Nazis.  

“It never happened,” Lindner told the House. 

“I was a child during World War II, and I’ve read a lot about World War II,” he said. “It’s just been recently that anyone’s come out with this idea that homosexuals were persecuted to this extent. There’s been a lot of rewriting of history.”

The remarks shocked the legislature, but attempts to censure him failed.