"We are wanting any information that will help us - people looking suspicious, hanging around cars or crawling under them. Anyone carrying canisters, that sort of thing."
She said although the reported incidents had been contained to the six suburbs so far, police could not rule out that thieves were targeting cars in other areas.
A spokesman for the Automobile Association said cutting fuel lines would be a slow way of stealing fuel from a car. "Fuel has always been the target of thieves, usually through siphoning, and higher prices will be providing more motivation for criminal elements," he said.
Modern cars often had anti-siphon devices fitted, which made it difficult to put a hose down through the filling point. Many had locking fuel caps.
"Our advice to motorists is to park vehicles as securely as possible and be vigilant," to protect their car and ensure they are not caught short if they do become a victim of a petrol thief.
"Also, always report any fuel theft or even vehicle tampering to ensure police are aware of any patterns developing in an area."