Alexis Ohanian is stepping down from the Reddit board of directors - and wants to be replaced by a black candidate.

The Reddit co-founder - who is married to Serena Williams and has Alexis Olympia Ohanian Jr., two, with the tennis star - has vowed to step down from his role so he can tell his daughter he has done his part to support the Black Lives Matter movement.

He wrote on Instagram: ''I co-founded @reddit 15 years ago to help people find community and a sense of belonging.

It is long overdue to do the right thing. I'm doing this for me, for my family, and for my country. I'm saying this as a father who needs to be able to answer his black daughter when she asks, 'What did you do?' I have resigned as a member of the reddit board, I have urged them to fill my seat with a black candidate.''

And Alexis has pledged $1 million to support Colin Kaepernick's Know Your Rights Camp, which helps to liberate black communities through ''education, self-empowerment, mass-mobilisation''.

He added in the lengthy post: ''I will use future gains on my Reddit stock to serve the black community, chiefly to curb racial hate, and I'm starting with a pledge of $1m to @kaepernick7's @yourrightscamp
 ... I believe resignation can actually be an act of leadership from people in power right now. To everyone fighting to fix our broken nation: do not stop. (sic)''