Huong's lawyer Hisyam Teh told the court the rejection of Vietnam's request was "perverse" and a case of discrimination, as the Attorney-General had favoured one party, since the court had ordered both to enter their defence.
The women claimed they had no idea they had been groomed by North Korean agents to carry out the murder and thought they were taking part in a prank TV show.
Counsel for Doan Thi-Huong, Hisham Teh Poh Teik, told the court that she had not slept for the past three nights following the decision by the Malaysian attorney general to drop the charges against Siti.
The Indonesian government had repeatedly lobbied for charges against Ms Siti Aisyah to be dropped and for her to be allowed to return home.
Abdul Rashid Ismail, a leading Malaysian criminal lawyer who was not involved in the case, said the decision to prosecute Huong but not Aisyah was "clearly unfair".
Vietnam had increased pressure on Malaysia to release Ms Huong, with the country's foreign minister this week pressing his Malaysian counterpart on the issue and the justice minister writing to the attorney-general.
Proceedings were scheduled to resume Monday with Huong testifying - but the unexpected release of Aisyah led to the trial being adjourned so the Vietnamese suspect could also seek her freedom.
Prosecutors did not give any reason for the remarkable retreat in their case against Aisyah, but the timing raised eyebrows in Malaysia as a High Court judge had just last August found there was enough evidence to infer that Aisyah, 26, and Huong, 29, had engaged in a "well-planned conspiracy" to kill Kim.
The two women were the only people in custody after four North Korean suspects fled the country the morning of February 13, 2017, when Kim Jong Nam was poisoned with VX nerve agent.
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Officer's from Richmond Police District were called and arrested a 39-year-old man at the scene. The suspect was granted conditional bail and is expected to appear in court on April 15.
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Another Max 8 plunged into the Java Sea minutes after taking off from an Indonesian airport in October, killing all 189 on board. It crashed 30 miles southeast of the airport, approximately six minutes into its two-hour flight, near the town of Bishoftu.
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Smollett was initially charged with one count of lying to the authorities on February 20. They became cooperating witnesses and were released without charges.
Their lawyers presented them as scapegoats and said the real killers were four North Koreans, who were suspected of being the masterminds behind the plot but fled Malaysia shortly after the assassination.
The duo had been charged over the murder. "More so in this case because two people were charged, but it was withdrawn against one but not against the other". The defense phase of the trial was to have begun Monday.
Huong's trial was postponed until April 1 after Doan's lawyer said she needed medical treatment.
The murder of Kim Jong Nam triggered a nationwide manhunt and a diplomatic crisis.
Analysts have said the case against Aisyah appeared weaker since there was no video evidence of her accosting Kim at the airport.
After the ruling, Huong was seen sobbing as she spoke with Vietnamese embassy officials, before being whisked away by police.
Huong would face a death sentence if she is convicted of murder.
Kim Jong Nam was living in exile in Macau before the killing, having fled his homeland after his half-brother Kim Jong Un became North Korea's leader in 2011 following their father's death.
Malaysian officials have never officially accused North Korea and have made it clear they don't want the trial politicized. He had been living overseas for years but could have been seen as a threat to Kim Jong Un's rule.