Independent MP Craig Kelly has brought a conspiracy into the House of Representatives, suggesting Australian Federal Police used "sonic weapons" on anti-vaccine mandate protesters in Canberra last Saturday.

He asked if the AFP had sought approval from the presiding officer to use "long range acoustic" devices on protesters.

The conspiracy has been circulating online this week after some of the protesters say they fell ill following Saturday's protest, which Mr Kelly claimed was the largest ever in Canberra - to the sound of jeering from some members.

"During that protest, can the Speaker confirm if the AFP positioned one or more long range acoustic devices in the parliamentary precincts with the intention that it be used as a sonic weapon against protesters," Mr Kelly said, to muffled laughter.

Before the Speaker can answer, an interjector calls out, "It's 5G!".

While Long Range Acoustic Devices or LRADs have been used to transmit messages and alarms, there has been no evidence of any unorthodox tactics or use of LRADs as weapons against the protesters.

"I'll report back to the house," a weary sounding Speaker Andrew Wallace replies, before adding a few seconds later "in due course".

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