Anti-war protesters say they found their way inside a Brisbane defence expo and past police and security via an unlocked side door.
About 20 protesters got inside the Land Forces Australia expo at the Brisbane Convention and Exhibition Centre about 2:30pm and several climbed onto a tank that was on display.
One of the protesters, a 27-year-old man, locked himself to the tank with a bicycle D-Lock around his neck.
Police ordered a number of them to move on, but 17 people were arrested and are expected to be charged tonight.
The crowd of exhibitors and delegates cheered as the police arrested the protesters and took them down from the top of the tank, one by one.
The Disrupt Land Forces group said the protesters entered "through an unlocked side door" but police said convention attendees opened an access door.
In a video posted online a police officer can be heard saying "you are under arrest for trespass".
Witnesses told the ABC that police handled the situation quickly and either moved protesters on or took them into custody.
The expo is in its second day and is showcasing military hardware and software from a range of international companies and contractors.
Second day of protests
In a statement, Disrupt Land Forces protest group spokesman Jarrah Kershaw said the event was being targeted because "these companies and the defence forces who buy their weapons are not welcome in Brisbane".
"We do not welcome war criminals, corporate thieves and murderers," he said.
On Tuesday, seven protesters were arrested amid scuffles with police as about 150 activists gathered outside the expo.
Protesters spread fake blood over the stairs and pavement outside the centre and heckled attendees and police.
Dozens of uniformed soldiers were also jeered as "war criminals".
