Malaysian prosecutors rejected a request from Vietnam to free her on Thursday.
The Vietnamese government had made the call after Doan Thi Huong’s co-accused, Indonesian woman Siti Aisyah, was released on Monday.
On Tuesday, Vietnam’s Justice Minister Le Thanh Long has called for freeing the Vietnamse suspect accused of killing Kim Jong-nam in Malaysia.
Also the same day, Vietnamese Deputy PM Pham Binh Minh, who is also the foreign minister, spoke with Malaysian Foreign Minister Saifuddin Abdullah on the phone on this issue and asked for Huong's release.
Huong and Siti Aisyah were charged with killing Kim by smearing his face with VX poison, a banned chemical weapon, at Kuala Lumpur airport in February 2017.