Berlin  - Following years of controversy, German dignitaries on Tuesday dedicated a memorial in Berlin to the tens of thousands of gays and lesbians who were persecuted and killed in Nazi Germany.

Bernd Neumann, Chancellor Angela Merkel's top adviser on culture, inaugurated the simple grey rectangular stone across the street from Germany's national memorial to Jewish victims of the Holocaust.

Neumann told gay leaders at the ceremony that more than 50,000 homosexuals had been convicted under the Nazis "because of their sexual orientation," with thousands of them sent to concentration camps and murdered.

Berlin's openly gay Mayor Klaus Wowereit was among those at hand for the ceremonies at Berlin's Tiergarten park, half a block from the iconic Brandenburg Gate.

The stone is 4 metres tall. The monument to the persecuted homosexuals is devoid of ornamentation, partly to deter vandalism and partly as a reference to the hundreds of plain, tomb-style stones making up the sprawling nearby Holocaust memorial.

The separate monument for homosexuals was ordered in 2003 by Germany's Bundestag parliament after lengthy debate over whether to commemorate all victims of the Nazis with one monument or separately.

Current research suggests 54,000 men and women were convicted of homosexual acts and about 7,000 killed in the camps. The dictatorship attempted to wipe out all dissent and any behaviour which did not serve the Nazi ideology.

The new monument, designed by Danish-Norwegian artists Michael Elmgreen and Ingar Dragset, contains a window that invites the visitor to look inside and see a film of a homosexual couple kissing.

The image is to be changed between two men and two women every two years. A text on the monument describes the Nazi persecution. The project cost 600,000 euros (935,000 dollars). (dpa)