Malaysia’s attorney general on Thursday rejected an appeal to drop murder charges against a Vietnamese woman standing trial for the assassination of North Korean leader Kim Jong-un’s estranged half-brother.

The ruling to proceed with her high-profile trial delivered a crushing blow to Doan Thi Huong, 30, who watched her Indonesian co-defendant, Siti Aisyah, walk free from the same Malaysian court and return home to her family on Monday.

A distraught Ms Doan broke down in tears in the dock as the decision was announced. "I am not angry that Siti has been freed. Only God knows that we did not commit the murder," she said. "I want my family to pray for me."

The ruling leaves Ms Doan, who arrived with armed guards at the Shah Alam court shortly before 9am and wearing a bulletproof vest, as the sole suspect in the case still behind bars.

The legal teams of both women have argued that they were pawns in the audacious assassination of Kim Jong-nam, 45, that was orchestrated behind-the-scenes by North Korean agents.

Pyongyang, said to have viewed Kim as a political threat, has officially denied any involvement in his murder and four North Korean suspects remain at large.