Police in Victoria have linked their decision to hand officers new non-lethal weapons – including a high-powered pepperball rifle – to violent political demonstrations overseas that the force says have now “come to Melbourne”.

Days after police were criticised over their response to a large brawl following a record launch in the Melbourne suburb of Collingwood on Sunday, police said they would not hesitate to use the new weapons to break up crowds and help identify offenders.

“This equipment will be out when they are out patrolling, it’s not going to be in some backroom storeroom,” assistant commissioner Chris O’Neill said on Wednesday.

“If the police commander considers it’s one of the tactical options that we need to use to resolve a matter, we will have no hesitation in using this equipment.”

The weapons, which were shown to the media outside police headquarters on Wednesday morning, included a semi-automatic rifle equipped to shoot 175 pepper-ball pellets, that could also be used to brand offenders using dye and a 40mm launcher that shoots squash-ball-like projectiles at a distance up to 50 metres. O’Neill said the police operations response unit would also be equipped with new flash-bang devices.

O’Neill said police had monitored trends “overseas over the last few years … in terms of demonstrations”, saying violence in Europe and the US “that is happening there … has come to Australia and it has come to Melbourne”.

He would not say if the weapons would have been deployed during the brawl at the weekend, but said he would have been “very comfortable with some of that crowd control equipment” when protesters clashed outside a Milo Yiannopoulos event in December last year. In that case, police used pepper spray.

“I’m not saying there will be more [incidents], I’m just a realist,” O’Neill said.

“I’d have my head in a bucket of sand if I didn’t think violence was going to happen. You look at some of our demonstrations, left and against right, this is Melbourne.”

He was confident the new equipment would lead to more arrests, but would not outline the number of offenders or type of violence that might warrant the use of the new weapons. The decision to use them would be up to the police commander on duty, he said.

Pressed on the timing of the announcement, he said it was “rubbish” to say the equipment was being rolled out this week as a PR exercise following criticism, including from the police union, over the force’s response to the brawl at the weekend and another large fight last month at Taylors Hill.

Asked if the weapons would have been used at the brawl at the weekend, O’Neill said he could not say because he was not on the scene.

Legal aid volunteers who witnessed the brawl in Collingwood on Sunday morning have disputed claims that up to 200 people were involved, saying the number was much smaller and was fuelled by alcohol.

They also said the fight, which left a man in hospital after he was hit by a car, was not gang-related.

O’Neill said he expected police from the operations response unit to be equipped with the weapons at planned demonstrations in Melbourne this weekend.