Toronto is ramping up its fight to close the last remaining illegal cannabis dispensaries.

The city's director of investigation services says fewer than 10 are still open.

He says some are "serial violators."

The city won't say exactly what it plans to do.

It has been sealing off shops and using large cement blocks to obstruct entry, but some operators are breaking back in.

After one raid on Wednesday, someone immediately re-entered a shop to try to reopen the dispensary.