The Nelson Mandela Foundation has hit out at Liberal Party members who used the anti-apartheid icon's image on leaflets that make false claims about the dangers of same-sex marriage.

The smear sheet distributed in suburban Sydney also uses the late leader's words – "Children are our greatest treasure. They are our future" – to argue against marriage equality.

The Nelson Mandela Foundation said any suggestion the former South African president was opposed to same-sex marriage was a ''misrepresentation''. Credit:AP

The leaflet is being distributed by a group known as Children's Future. Fairfax Media revealed on Friday that the three directors of the group are members of the NSW Liberal Party.

Mandela's not-for-profit foundation has now hit back, issuing a statement overnight saying any suggestion that the former South African president was opposed to same-sex marriage was a "misrepresentation".