POLICE clashed with activists protesting Colin Barnett's catch-and-kill shark policy in Cape Town yesterday when they breached a security cordon at the Convention Centre where the WA Premier was delivering a keynote speech.

About 200 chanting protesters protested, including a section holding a giant banner reading "Colin Barnett, Cape Town Loves Sharks, You're Not Welcome".

Others held placards proclaiming things like "Stop the Cull OZ", "No Shark Cull", "Cullin Barnett Must Go" and "FCKU Barnett".

A tight security cordon had the Convention Centre in lockdown for the massive Indaba Mining Conference.

One of the protest organisers, Sharon Martin, said security had prevented the group confronting Mr Barnett when he arrived at the convention centre and had also tried to force them two blocks back from outside the venue.

"The police came on motorbikes and then a large angry group (of activists) broke away and ended up outside the main entrance of the convention centre while Barnett was inside making his speech" she said.

Ms Martin said police and security had prevented the protesters from entering the convention centre and had threatened to arrest activists.

"I spent most of my time negotiating with police who wanted to arrest us," she said.

"We were in place 45 minutes before his speech, but we didn't get to see Barnett personally to make our feelings known. But we were excited to show support for our fellow great white activists in Australia and speak up for the sharks that we share.

"We got out point across that sharks don't belong just to Western Australia and we made a lot of noise about how much we care for great whites," Ms Martin said.