Alan Joyce, boss of Australia's Qantas Airways, is planning to press assault charges against the man who smashed a pie on his face on 9 May (Tuesday).

Tony Overheu, a former farmer, shoved Joyce's face with a lemon meringue pie while the Qantas chief was addressing a crowd of around 500 people at a business conference in Perth, discussing the airline's recent decision to operate non-stop flights from London to Perth.

According to reports, Overheu was not happy with the airline chief executive's support for same-sex marriage, which is illegal in Australia, and wanted to make an statement.

"On the west coast, there is very limited opportunity to have connection with national figures.

"From my reading, it would appear that Alan Joyce is very much part of a network trying to subvert the federal parliamentary process around the issue of marriage equality," the 67-year-old man told Australian Broadcasting Corp.

While Overheu has been charged for providing false details after the incident, Joyce said, "The police are continuing their investigation and my intention is to send a message that this type of behaviour isn't acceptable and that I will have every intention of pressing charges.

"I have every intention to continue to be vocal on those social and community issues. I'm a big believer in the great Australian expression a fair government it's all about giving people equality."

Qantas Airways boss Alan Joyce
Qantas Airways boss Alan Joyce was pied in the face by Tony Overheu, who is against same-sex marriage, on 9 May - File photo REUTERS/David Gray

Joyce was one among 20 chief executives of some of Australia's top companies who signed an appeal in March, urging Prime Minister Malcolm Turnbull to decriminalise same-sex marriage in the country.

"Alan Joyce is a very active individual in this process [towards marriage equality] and in that context he was appropriate [to target]. I've never done that sort of thing, I'm a law-abiding person, but I think this is part of inevitable pushback," Overheu said.