ALLOWING same-sex couples to marry could lead to the acceptance of polygamy and incest, the Anglican Archbishop of Sydney, Peter Jensen, has warned.

Writing in the church's newspaper, Southern Cross, Dr Jensen said the push for same-sex unions to be enshrined in the Marriage Act was not a drive for the extension of rights but the redefinition of ''one of the indispensable foundations of community''.

"In praise of marriage" ... the Anglican Archbishop of Sydney, Peter Jensen, says same-sex marriage would have unwelcome consequences. Credit:Peter Rae

''Ensuring public honour of same-sex relationships by calling them marriages is an abuse of marriage itself,'' he said.

''It imposes, through social engineering, a newly minted concept of marriage on a community that understands it in quite another way.''