His daughter Angela Gui told Radio Sweden that her father was taken from a train on Saturday while traveling with two Swedish diplomats.
Gui Minhai has been reportedly diagnosed with ALS, a progressive neurodegenerative disease, and was en route to Beijing for a medical check-up with a Swedish doctor.
"I think it is quite clear that he has been abducted again and that he’s being held somewhere at a secret location," Angela Gui tells Radio Sweden on Monday.
"And given his health status, that's very worrying," she says.
Gui Minhai, a Swedish citizen originally from Hong Kong, disappeared on October 17, 2015 while on holiday in Pattaya in Thailand. The writer ran a publishing company known for publishing books critical of the Chinese government.
A spokesperson at the Swedish Foreign Ministry confirms that Gui Minhai has been detained and tells Swedish Radio News that they are taking it very seriously. "We have taken strong measures on a high political level," he said.