A memorial to the thousands of gay men who died in Nazi concentration camps will be officially dedicated today.

It is being constructed opposite the main Holocaust memorial for Jewish victims in Tiergarten Park in Berlin at a cost of 600,000 euros (£450,000).

The government agreed to the design earlier this year, four years after the memorial was agreed in principle.

Ingar Dragset and Michael Elmgreen have designed a grey concrete slab, with a window to allow visitors to view a video.

There will be a video which show either two men kissing, Berlin’s first memorial to the Nazi’s gay victims.

Its design echoes Peter Eisenman’s Berlin memorial to the Nazis’ Jewish victims, a vast field of more than 2,700 slabs.

The German parliament approved the construction of the memorial in December 2003.

Between 5,000 and 15,000 gay men were held in concentration camps by the Nazis as members of an “anti-social group.”

Historians estimate that 60% of them died while incarcerated.

After the war gay men were not recognised as victims of the Holocaust and many were re-imprisoned by the authorities because of the sexuality.

They were denied the reparations and state pensions available to other groups. In 2002 the German government formally pardoned homosexuals imprisoned by the Nazis.

As well as an estimated six million Jews, hundreds of thousands of Roma people died in Nazi concentration camps.

A memorial to them will be constructed later this year.