A young Australian woman convicted of smuggling marijuana onto Indonesia's Bali island launched a final appeal Friday against her 20-year sentence.

Schapelle Corby's conviction in May of 2005 for smuggling 4.2 kilograms (nine pounds) of marijuana onto the resort island triggered intense media interest in Australia, where many people said she is innocent.

Her lawyer Erwin Siregar said Corby, 29, had not been proven to be part of a criminal network so could not be found guilty of importing drugs. He also said he would submit a letter from Australia's justice minister that would constitute the new evidence needed to launch the appeal, known as a judicial review.

The letter, a copy of which was viewed by the Associated Press, is a reply by the minister, Christopher Ellison, to a question by Siregar about whether security cameras were working on the day Corby left Sydney airport.

Ellison writes that "on the date of Ms Corby's departure, none of the cameras had been identified as having a fault."

Siregar also said he had asked Ellison for footage taken from cameras in the baggage handling department of Sydney airport on the day of Corby's departure that he intended to submit to judges.

The relevance of the letter and footage was not made clear, but it appeared to be related to defense claims that Corby was a victim of a domestic drug ring involving corrupt Australian baggage handlers who failed to retrieve the planted marijuana before her bags were transferred to an international flight.

The drugs were found in a surf board bag belonging to Corby.

Siregar said there was "no way the defendant would do such a foolish thing" as smuggling the drugs.

Asked whether he thought the appeal would succeed, he said: "We are confident this will work. If we were not confident, we would not be doing it."

Corby was mobbed by photographers and TV crews on her arrival at Denpasar District Court.

The former beautician, who has always maintained her innocence, did not speak to the court.

The case will be considered by judges behind closed doors. Verdicts typically take around one or two months, said Siregar.

Dozens of foreigners are arrested or convicted of drug smuggling every year in Indonesia, most of them Africans or Asians.

Corruption is rife within Indonesia's legal system.

Critics say most cases are decided not on evidence presented in court, but on illegal bribes paid to prosecutors or judges.