Victorian cops give dope party green light

Police did not arrest anyone at a marijuana picnic in a Melbourne CBD park despite knowing about the event.

Hundreds of attendees at cannabis campaigner Matt Riley's November "420 Picnic" at Flagstaff Gardens on Sunday possessed or consumed cannabis.

"Police were in close contact with event organisers and were prepared and ready to respond on the day if required to ensure community safety," a police spokeswoman told AAP in a statement on Friday.