The key witness told a Canadian court that that she was threatened by associates of main accused Ripudaman Singh Malik.
The woman, whose name was not revealed under a direction from the court, used to work for Malik.
Ripudaman Singh Malik had shared the plot, including mistakes he believed were made, with a confidante, a witness in the trial has testified at a court in Vancouver.
Prosecuters have said that she will testify that Malik told her about his role in the disaster and also told the woman the names of several others involved in the scheme, Canadian daily The Globe and Mail reported.
Lawyers for one of the chief accused, Ripudaman Singh Malik, asked for more time for negotiations over how his legal fees were to be paid.
Reyat was convicted of perjury in 2010 for lying to the court in 2003 during the trial of Ripudaman Singh Malik and Ajaib Singh Bagri, who were acquitted in the terrorist attack on Air India Flight 182 that killed all 329 people aboard.