Climate protesters in Melbourne target international mining conference

Climate change protesters have hit the streets in opposition to a major mining conference in Melbourne, with promises of further 'disruption' to come.

Climate activists gathered outside the Melbourne Convention and Exhibition Centre to demonstrate against a major mining conference. Source: Twitter/Karuna_99

Climate activists have kicked off another wave of disruptive protests in the heart of Melbourne, this time targeting a mining conference attended by thousands of global delegates.

Activists are hoping to shut down the International Mining and Resources Conference at the Convention Centre, which starts on Tuesday.

A group of about 100 people made their presence known outside the facility on Monday before marching up Spencer Street, temporarily delaying traffic.

Police say 11 different groups plan to cause "maximum disruption" outside the conference, with protests likely to continue spilling across parts of the CBD.

More than 300 police officers will be assigned each day to ensure activists don't break the law or adversely impact the community.

The Extinction Rebellion group ran a week of climate protests early in the month and Victoria Police acting commander Tim Tully said activists might ramp up their methods this time.

"We expect to see heightened tactics by the protest groups," he told reporters in Melbourne on Monday.

Extinction Rebellion activists have previously held "drown in" protests to demand action on climate change. Source: AAP

"Our intelligence would suggest that the protesters have been planning, and are well co-ordinated, to undertake different tactics to what we saw, or very similar tactics to what we saw, in the recent protest activity.

"We are well prepared to respond."

A spokeswoman for one of the groups, IMARC Alliance, said they aren't planning to cause havoc in the CBD.

"It's never been our intention to disrupt the city ... we want to shut down the conference using blockading tactics," Emma Black told 3AW.

"Our enemy are not motorists or the police, our enemies are the corporate mining executives."

But her group can't control the likes of Extinction Rebellion, she said.

Acting commander Tully said protest groups have been unwilling to give police a good sense of what they can expect to deal with.

"It's been very frustrating, the lack of engagement that we've had," he said.

Victorian opposition leader Michael O'Brien said people should be allowed to go about their business without being confronted by "constant demonstrations".

"It's turning Melbourne into a joke and unless the premier starts giving the police the powers they need to do with it, it's just going to continue and go on," he told reporters.

The mining and resources conference runs for three days and is expected to be attended by up to 7000 people from around the world.