Qantas chief executive Alan Joyce has had a lemon meringue pie launched at his face during a business breakfast event in Perth.

Mr Joyce was addressing about 500 people at a Business Leadership Matters event at the Hyatt Regency hotel, where he was the keynote speaker.

The pie was launched by a man in his 60s wearing a business suit, who walked onto the stage to do so.

The man was detained by security at the hotel. ( AAP: Gregory Roberts )

Mr Joyce, who had been discussing recently announced direct flights to London from Perth, reportedly walked off-stage to clean himself up after his face and suit were covered in cream.

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He then returned to continue his speech without his jacket, joking with the audience about the incident.

"Now, if there are any more pies can you get it over with now?" he said.

Security staff detained the pie-thrower until police arrived to arrest him.

"We can confirm that we responded to an assault, and it's highly likely that charges would be laid, however it is too early to say what those charges will be," a police spokesperson said.

Mr Joyce later appeared at a scheduled media call at Perth Airport, wearing a fresh jacket, to further spruik the direct Perth-to-London flights.

He said work was beginning on the terminal upgrades required to facilitate international travel from the domestic side of the airport.

The Perth-to-London flights commence in March 2018.

Mr Joyce again made light of the incident and said he did not know what type of pie had been used.

"I didn't have a chance to test it — it was mostly on my glasses," he said.

"I think my issue is I need a good drycleaner before I leave Perth so if you have one please recommend it to me."

He said it was the first time a pie had been thrown at him.

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"Well I think when you've been CEO of an airline for nine years there's a lot of things that happen over that period of time," he said.

"This is different ... it is an unusual event but these things happen."

Mr Joyce said it was important to let police investigate the incident.

Immigration Minister Peter Dutton tweeted the incident was "a disgrace" and the perpetrator "should be ashamed".