Tampering with security cameras at Sydney airport meant heroin could have been placed in an innocent passenger's baggage and there would be no record, a Labor MP said today.

ALP backbencher John Murphy said two security cameras aimed at baggage conveyor belts at the airport were moved to point in the wrong direction on three occasions between October 2004 and May 2005.

Mr Murphy said it raised fresh concerns about the case of Schapelle Corby, jailed in Bali for drugs smuggling after 4.1kg of marijuana found in her bodyboard bag at Denpasar Airport.

Corby has always said that someone else - possibly a baggage handler at Sydney airport - had planted the drugs in her luggage.

"There was a big cocaine scandal also at that time. What's going on out there at Sydney airport? Anyone working in the cargo and baggage handling areas could have put heroin in an innocent passenger's luggage," he told ABC radio.

Mr Murphy said the cameras were supposed to point at the conveyer belts carrying luggage and cargo for the obvious reasons.

"If someone interferes with someone's baggage after it has been checked in, there's a permanent record of it," he said.

"They weren't pointing at the baggage. They were probably pointing at a brick wall and that is why (Justice Minister Senator Chris) Ellison has to answer those questions today because security at Sydney airport is in chaos."

Mr Murphy said Senator Ellison had confirmed last week that the cameras were pointing in the wrong direction.

"I ask how could such a serious breach happen to two cameras on three occasions," he said.

"I am sure Schapelle Corby's legal team would like to know precisely when the first breach occurred, because I understand that she went through Sydney airport on October 8, 2004."