She then said the men ordered her to spray the liquid on Kim Jong-nam while her companion covered his face with a cloth.
But she claims she could not later find the men or her companion and returned to the airport on Wednesday where she was arrested, Fairfax reported.
Malaysian police are yet to comment on the report.
The woman's arrest comes as North Korea objected to an autopsy being performed on the body of the slain man.
It remains unclear whether she is the woman in the white "LOL" jumper captured on CCTV images and circulated by police.
Eyewitnesses to the death said two women fled the scene in a taxi.
The arrest of the woman comes as North Korean government officials reportedly objected to an autopsy being performed on the body of Kim Jong-nam.
Malaysian officials aware of the discussions said North Korea requested the body be returned immediately, however no decision has been made.
Police said they are looking form a "few" foreign suspects in addition to the Vietnamese woman already being questioned.
The half-brother to North Korean leader Kim Jong-un died after reportedly being targeted with a chemical spray in the airport at Selangor, near Kuala Lumpur.
Details about the killing remain unclear but South Korea's spy agency said it was believed to be a North Korean operation due to Kim Jong-un's "paranoia" about his brother.
Malaysian investigators are scouring surveillance video for clues as to what happened in the extraordinary death that comes after a purge of many top level officials in South Korea, including Kim Jong-un's uncle, Jang Song Thaek, who was killed in 2013.
Kim Jong-nam, 46, was believed to have been in a shopping concourse on route to a flight to Macau when he died.
While he was originally tipped as a potential successor to his father, Kim Jong-il, he had left the country and spent time living in Macau, Singapore and Malaysia.
In 2001 he was caught trying to enter Japan on a false passport saying he wanted to visit Tokyo Disneyland. He was also renowned for having a playboy lifestyle and attended international schools in Russia and Switzerland.
A Malaysian police statement confirmed the death of a 46-year-old North Korean man whom it identified from his travel document as Kim Chol, born in Pyongyang on June 10, 1970.
