The chief lobbyist for big business has defended the right of company bosses to take a position in the same-sex marriage debate, and hit out at "deeply offensive and deeply wrong" comments about the children of LGBTI families.

Business Council of Australia chief executive Jennifer Westacott​ said companies "employ millions of Australians, they stand very strongly for diverse workplaces and some of them have very strong views that this is a kind of symbol of that kind of diversity in the workplace".

Ms Westacott - who has been in a same-sex relationship for 30 years - said it was "not fair" to expect business to take a role on issues such as gender equality and community development but not same-sex marriage.

"I don't think people can have it both ways and I think business, who employ so many people, who are big parts of communities, are entitled to take views on this and have strong opinions on this either way - provided it's respectful and informed," Ms Westacott told ABC Radio National on Thursday morning.