Australian Prime Minister Julia Gillard on Thursday withdrew from speaking at a Christian lobby conference after its head suggested smoking was healthier than a gay and lesbian lifestyle.
Gillard was due to address the Australian Christian Lobby's meeting in October but pulled out over the "offensive" and "inappropriate" comments about homosexuality.
It followed ACL chief Jim Wallace, whose ultra-conservative group lobbies for Christian principles and ethics, on Wednesday making the claim during a debate on same-sex marriage.
"I think we're going to owe smokers a big apology when the homosexual community's own statistics for its health -- which it presents when it wants more money for health -- are that it has higher rates of drug-taking, of suicide, it has the life of a male reduced by up to 20 years," he said.
"The life of smokers is reduced by something like seven to 10 years and yet we tell all our kids at school they shouldn't smoke."
After the debate, Wallace said the figures saddened him.
"But what I'm saying is we need to be aware that the homosexual lifestyle carries these problems and ... normalising the lifestyle by the attribution of marriage, for instance, has to be considered in what it does encouraging people into it."
Gillard, an atheist who opposes legalising gay marriage, said debate about the issue should be "respectful and responsible".
"I believe yesterday's comments by Jim Wallace were offensive," she said in a statement.
"To compare the health effects of smoking cigarettes with the many struggles gay and lesbian Australians endure in contemporary society is heartless and wrong.
"Although everyone is entitled to their own view, these statements reiterated again today on behalf of ACL are totally unacceptable.
"In light of this, I believe my attendance at the conference would be inappropriate."
Marriage is covered by federal legislation in Australia which defines it as between a man and a woman, so while civil same-sex unions are recognised in several states, the couples are not considered "married" by the national government.
Same-sex couples have, however, the same rights as heterosexual couples in areas such as pension schemes and medical benefits.