SCHAPELLE Corby's lawyer Erwin Siregar says he is `1000 per cent sure' that the final appeal process cannot increase the Tugun woman's 20-year sentence.

Following the dire news of upgraded sentences to the death penalty for many of the Bali Nine, The Gold Coast Bulletin asked the Balinese lawyer last night if the extraordinary appeal he is trying to convince the Indonesian law system to convene is safe from a harsher sentence.

He replied: "Absol-utely 1000 per cent sure."

Mr Siregar said he spent 40 minutes in a Balinese court yesterday in his latest effort to convince the court to grant the 29-year-old an extraordinary appeal.

"It will be one or two months before we know if that is successful and the appeal can then go ahead," he said.

The special appeal is the last possible chance Ms Corby can have through the Indonesian judicial system for any change to her sentence and for it to be granted, the Supreme Court in Jakarta has to be convinced there is substantial new evidence or that the original hearing was badly flawed.

The Corby legal team admits it does not have any new evidence but is certain the trial was flawed in many ways and hopes that will be accepted and an appeal granted.

Mr Siregar said he tendered a letter to the court yesterday from Australian Justice Minister Chris Ellison.

"The letter was from June, 2005, and in it Mr Ellison said he did not believe that Schapelle Corby was involved in drug trafficking," he said.

"When Schapelle was with her Lily and Vasu (her first legal team that Ms Corby sacked last year) and I helped them, I had not seen that letter then," he said.

"I hope the court will accept this letter and set this woman free."

He said the prosecution would put its case against an extraordinary appeal to the court in Denpasar next week. Ms Corby was arrested on October 8, 2004, when Customs officers found 4.1kg of marijuana in her unlocked boogie-board bag at Denspasar Airport. Schapelle Corby Case Information