MELBOURNE, Australia — Anti-war protesters clashed with police on Wednesday outside a military arms convention in southeastern Australia. Protesters hurled bottles and rocks, a police statement said. They also sprayed officers with liquid irritants, some of which were identified as acid. Law enforcers retaliated with pepper spray, flash distraction devices and rubber bullets, which are designed to inflict pain without penetrating the skin. At least 24 officers required medical treatment. Police arrested 39 protesters for offenses such as assault, arson and blocking roadways. "Victoria Police is appalled at the behavior of some of the protesters," the statement said, referring to the Victoria state force. About 1,800 police officers have been deployed to a convention center in the city of Melbourne, where the Land Forces International Land Defense Exposition is being held through Friday. Some of the convention attendees were also assaulted, police said. Protesters also threw rocks, horse manure and tomatoes at police horses and officers with shields and wearing riot gear. A police officer on horseback struck a protester with a riding crop and a line of police were seen forcing protesters away from the convention center. Police said some protesters targeted the horses, but no animal sustained serious injury. Roads have been closed and traffic was disrupted by the protests, organized by Students for Palestine and Disrupt Wars groups. The organizers hoped up to 25,000 protesters would turn out. Police estimated 1,200 protesters had surrounded the convention center by noon. Police Chief Commissioner Shane Patton said it was the state police force's biggest planned deployment since Melbourne hosted the World Economic Forum in 2000 and backed his officers' use of force. He said the protesters had planned for conflict. "They come here to protest... anti-war so presumably anti-violence," Patton told reporters. "The only way I can describe them is a bunch of hypocrites." Students for Palestine national co-convenor Jasmine Duff blamed police for the protest violence. "They used serious weapons on peace activists that should be banned for use on demonstrators, including pepper spray, which is classified as a chemical weapon," Duff said in a statement. "They hit us with batons, including hitting one man so hard he had to go to hospital, and they shot us with rubber bullets," she added. Australian 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." The organizer of the biennial convention, the AMDA Foundation, said it would not comment on protester activity. The gathering brings together arms industry figures from Australia, the United States, Asia and Europe. In 2022, the convention was held in the northeastern city of Brisbane, where protests were more subdued.