Nolubabalo "Babsie" Nobanda, of Grahamstown, in the Eastern Cape, was arrested at the Bangkok International Airport in December 2011.

Her mother Honjiswa Mbewu said she had appeared in a court in Bangkok on a charge of drug trafficking. The matter was postponed to June 18 for judgment.

She said the two security officers who arrested her testified that Nobanda co-operated and freely confessed to trafficking in drugs. She said the court heard evidence that the cocaine Nobanda was carrying was mixed with baking powder.

In a letter to her family, which they received this week, Nobanda said she was in good spirits and upbeat about the judgment.

She said she would be convicted of attempting to smuggle 600g of cocaine and not 1.5kg as reported earlier.

The family was expected to send a legal adviser and a family member to attend the judgment.

"I can confirm to you that a family member will travel to attend court and we are very optimistic at this stage," she said.

Nobanda had been represented by a Bangkok state lawyer.

The family had also obtained letters of reference and support from people who knew Nobanda, among them two Eastern Cape judges.

Churches and charity groups have also written to the court asking for a lenient sentence.

In her letter, Nobanda asked her family to forgive her.

"First and probably the most important thing I want to say is I am sorry to all of you. I know that I have disappointed, hurt and humiliated the whole family. I ask for forgiveness," she wrote.