A woman has been charged with common assault after allegedly striking Scott Morrison on the back of the head with an egg.

Key points: An elderly woman was knocked over when security tackled the protester

An elderly woman was knocked over when security tackled the protester Opposition Leader Bill Shorten said the egging was "appalling and disgraceful behaviour"

Opposition Leader Bill Shorten said the egging was "appalling and disgraceful behaviour" A woman carrying a carton of eggs was escorted from the Albury event

The woman, 24, allegedly walked up behind Scott Morrison and threw an egg, which bounced off his head and did not smash.

The protester, who had a carton of eggs with her, was tackled to the floor by security.

The incident happened at a Country Women's Association (CWA) event in Albury, on the NSW-Victorian border.

An elderly lady, Margaret Baxter, was knocked over during the scuffle and was helped to her feet by the PM but she did not appear to be injured.

NSW Police later confirmed the protester had been taken into custody and charged with common assault and possession of cannabis, after police allegedly found the drug on her during a search.

The protester cracked a smile while being escorted from the venue. (ABC News: Adam Kennedy)

"My concern about today's incident in Albury was for the older lady who was knocked off her feet," the Prime Minister tweeted.

"I helped her up and gave her a hug.

"Our farmers have to put up with these same idiots who are invading their farms and their homes.

"We will stand up to thuggery whether it's these cowardly activists who have no respect for anyone, or militant unionists standing over small businesses and their employees on work sites."

Shortly afterwards, Australian Council of Trade Unions secretary Sally McManus attacked the PM's comment.

"How dare you accuse us of this and make the association. You seem to have no respect for the truth or any concern about running down your fellow Australians. We would never support such behaviour," she tweeted.

The protester did not answer questions from journalists after being thrown out of the building.

In a statement, NSW Police said the egg which was thrown at Mr Morrison actually hit a different woman.

The CWA said the protester was not one of their members.

The egg did not crack, even after bouncing off the PM's head and onto the ground. (ABC News: Dan Conifer)

Mr Morrison was greeting dozens of CWA members after addressing the organisation's state conference.

He appeared unfazed in the minutes after the incident, continuing to greet some of the hundreds of attendees.

He later attended a Liberal Party event across the border in Wodonga in the electorate of Indi.

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NSW Police said no injuries had been reported and that their inquiries were continuing.

Ms Baxter said she fell on her hip but was not in pain.

"I'd recently had surgery on my stomach so my main concern was holding my stomach to make sure it didn't get hit or someone land on it," she said.

"I'm very disappointed that something like that would happen at a CWA meeting but I believe that person was not a CWA member."

Speaking from Melbourne, Opposition Leader Bill Shorten the egging was "appalling and disgraceful behaviour".

"In Australia we have violence-free elections, people are allowed to protest peacefully but anything approaching violence is unacceptable," he said.

"If this protester thinks she will get sympathy or support from me, she couldn't be more wrong."

Eggs have become a weapon of choice in Australian politics this year.

Queensland senator Fraser Anning had an egg smashed over his head by a Melbourne teenager in March, after he linked Muslim immigration to the Christchurch mosque massacre.

The charged woman was granted strict conditional bail and is due to appear at Albury Local Court on May 27.