Chaucer Ward councillor Dr Abdur-Rahman Olayiwola has quit the Lib Dems and is standing as an independent having failed to be reselected.
"Since taking over Southwark in 2002, the Lib Dems have ensured that most executive cabinet ministers are white even though black and ethnic people have knowledge, experience and expertise," Dr Olayiwola (known as Dr Ola) told the Black Information Link website.
We asked Southwark Liberal Democrats to comment on Dr Ola's allegations. A spokesperson said: "Dr Olayiwola has resigned from the Liberal Democrats following the local party's decision not to reapprove him as a candidate for the forthcoming local elections after he failed to meet stated criteria.
"The Liberal Democrats seek to promote diversity and equality and end discrimination against people on any basis.
"Dr Olayiwola's comments on the sexuality of Southwark councillors are inconsistent with this vision for a fairer and more tolerant society."
Dr Ola is quoted by Blink as saying: "I am not against gay people whatsoever and I am not being phoney when I say some of my best friends in politics are gay. Gay people should have equal rights like everybody else.
"What I am against however, is disproportionate levels of gay people, black people or whatever."
Dr Ola has represented Chaucer ward since 2002. He was previously chair of the licensing committee. He is contesting the local election on Thursday 4 May as an independent candidate.
• More reaction to follow