The Customs Minister insists the Government's had success seizing illicit tobacco, as a report outlines the reality of the black market.

FTI Consulting's study - commissioned by tobacco companies - found more than a third consumed last year was illegal.

It estimates the Government lost $817-million in excise and GST revenue last year.

Casey Costello says despite more seizures than ever, smuggled amounts are getting through.

She's advising customers to be cautious.

"When you've buying that cheap packet of cigarettes, you're lining the pockets of some pretty bad people."

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