The US State Department says it's deeply concerned that a Swedish citizen and Hong Kong-based bookseller, Gui Minhai, has been detained in China and called for him to be allowed to leave the country.
The Swedish government has said that Gui, who has published books on the personal lives of President Xi Jinping and other Communist Party leaders, was taken into custody last week while travelling with Swedish diplomats to seek medical treatment in Beijing.
The European Union's ambassador to China has called on the Chinese authorities to release Gui immediately, echoing demands from Stockholm.
"We are deeply concerned that Swedish citizen Gui Minhai was detained," State Department Spokeswoman Heather Nauert said in a statement.
"We call on Chinese authorities to explain the reasons and legal basis for Mr Gui's arrest and detention, disclose his whereabouts, and allow him freedom of movement and the freedom to leave China," she said.
Asked this week about the Swedish and EU demands for Gui's release, a Chinese foreign ministry spokeswoman described the appeals as "baseless."
Gui had been abducted in Thailand while on holiday in 2015, one of five Hong Kong booksellers who went missing that year and later appeared in custody on mainland China. The four others have returned to Hong Kong.
Chinese authorities said Gui was freed in October after serving a two-year sentence for a traffic-related crime in 2003.
Gui's daughter Angela told Radio Sweden he was taken off a train by plainclothes police while en route to the capital to get medical attention for a neurological ailment.
