MELBOURNE, Australia (AP) — Thousands of anti-war protesters clashed with police Wednesday outside a military arms convention in downtown Melbourne.

Around 1,800 police officers have been deployed to a Melbourne convention center where the Land Forces International Land Defense Exposition will take place from Wednesday until Friday.

Witnesses reported protesters throwing rocks, horse manure and tomatoes at police horses and officers with shields and wearing riot gear. A police officer on horseback was seen striking a protester with a riding crop.

A line of police was also seen forcing protesters away from the convention center.

Officers used pepper spray against some protesters and were seen taking others into custody.

Roads have been closed off and morning peak hour traffic was disrupted by the protesters organized by Students for Palestine and Disrupt Wars groups. Organizers hoped up to 25,000 protesters would turn out.

“We’re protesting to stand up for all those who have been killed by the type of weapons on display at the convention,” Students for Palestine national co-convenor Jasmine Duff said in a statement.

“We are going to disrupt the convention using civil disobedience tactics passed down to us by activists in the civil rights movements and the anti-Vietnam war movement,” she added.

Prime Minister Anthony Albanese called on protesters to show respect for police.

“People have a right to protest peacefully, but you don’t say you’re opposed to defense equipment by throwing things at police,” Albanese told Seven Network television.

“They’ve got a job to do and our police officers should be respected at all times," Albanese added.

The convention organizer AMDA Foundation said in an email on Wednesday it would not be commenting on protester activity.

The biennial convention brings together arms industry figures from Australia, the United States, Asia and Europe.

The convention was last held in 2022 in Brisbane where protests were more subdued.