SEOUL, South Korea — The only North Korean defector in South Korea who has publicly said she wants to return to her home country, insisting that she arrived here by mistake, applied for political asylum at the Vietnamese Embassy in Seoul on Monday.

The woman, Kim Ryen-hi, 46, walked into the embassy and asked it to accept her as a refugee and to help her return to North Korea, said Christian pastors who accompanied her. More than two hours later, South Korean police officers, who entered the embassy at its request, escorted her out.

“I told embassy officials that I wanted to stay in until they gave me asylum, but they insisted that I should wait outside until their government makes a decision,” Ms. Kim said after emerging from the building.

Breaking into tears before a group of reporters in front of the embassy, she said she feared that her request would be turned down, given her unwelcoming reception.