BANGKOK — Thailand’s military government is seeking the extradition of the country’s last elected prime minister, Yingluck Shinawatra, who fled to Britain rather than go to prison for five years on negligence charges.

Ms. Yingluck, who was forced from office in 2014, was put on trial in Thailand last year, accused of costing the country $8 billion by mismanaging a rice subsidy initiative while prime minister. She fled the country shortly before the verdict was announced, and the court sentenced her in absentia.

It was unclear why the Thai government decided to issue the extradition request now, nearly a year after she fled the country, but Ms. Yingluck has popped up recently on social media in photos and videos apparently taken in London.

“This request does not relate to the investigation, investigation or punishment of a person for an offense of a political or military nature,” said the extradition request, which is dated July 5 but came to light on Tuesday in a report from BBC Thai.