SYDNEY - Fears that a contentious postal vote on legalising same-sex marriage in Australia was fuelling violence grew Friday after a man allegedly wearing a "yes" badge was charged with headbutting former prime minister Tony Abbott.
Abbott, an outspoken critic of gay marriage, was campaigning for the "no" vote when he said he was attacked by the 38-year-old in Hobart in Tasmania state late Thursday.
Up to 15 million Australians taking part in the voluntary postal ballot can choose "yes" or "no" on whether gay marriage should be legalised, with the results to be released in mid-November.
"I held out my hand. He grabbed my hand and turned it into a headbutt. Now, he was, of course, wearing a 'yes' badge," Abbott told reporters in Hobart on Friday.
"I worry about the brave new world of same-sex marriage if this is how some of the people who are most enthusiastically working for it are behaving with such bullying and intimidatory fashion."
The 59-year-old suffered minor injuries to his lip but "didn't require medical assistance", Tasmania Police Commander Tony Cerritelli told reporters.
Police said the man, from North Hobart, was charged with one count of assault, and granted bail to appear in court on October 23.
Abbott, long renowned for his conservative views, was prime minister from 2013 to 2015, when he was deposed by current leader Malcolm Turnbull - a moderate who supports marriage equality.
Turnbull on Friday condemned the alleged headbutt, adding that "one incident is one too many".
"However, it's important to remember that overwhelmingly Australians are engaging in this debate respectfully and harmoniously," he said.
Leading "yes" campaigner Alex Greenwich, an independent New South Wales state MP, said there was "no room for any disrespect either physical or verbal in this national debate".
Concern the vote could unleash abuse and homophobic slurs saw parliament pass election-style safeguards restricting campaign material that might be misleading and deceptive during the ballot period.
The incident occurred as pop star Elton John, who is performing a series of shows in northern Queensland which was devastated by a category-four cyclone earlier this year, called on Australians to embrace marriage equality.
"I love Australia. I love its spirit, its lack of pretence, its passion. I hope it can embrace the honesty and courage that seeks gay marriage as an expression not of desire but of love," he wrote on Facebook late Thursday.
The postal survey is non-binding but Turnbull has vowed to hold a vote in parliament if the majority of Australians choose "yes".