China has sentenced Swedish book publisher Gui Minhai to 10 years in prison on charges of illegally providing intelligence abroad, and claimed him as a citizen, prompting Stockholm to call for his release in a case that has rattled diplomatic relations.

Gui, one of five Hong Kong-based booksellers known for publishing salacious titles about China’s political leaders, was snatched by authorities while on a train to Beijing in February 2018, the second time he disappeared into mainland custody.

A court in the eastern city of Ningbo said Chinese-born Gui was sentenced Monday to 10 years in jail, and claimed he had also voluntarily reinstated his Chinese citizenship in 2018.

Since Beijing does not recognize dual citizenship, “China, according to law, only recognizes him as a Chinese citizen”, foreign ministry spokesman Zhao Lijian said Tuesday.

But Swedish Foreign Minister Ann Linde on Tuesday said in a statement that Stockholm continues to call for Gui’s release and “demand access to our citizen to give him the consular support he has the right to”.

The Swedish foreign ministry told AFP that citizenship can “only be renounced after an examination and a decision by the Swedish Migration Agency” and that Gui remained a citizen.

Later Tuesday, the ministry summoned China’s ambassador and “reiterated our demands that Gui Minhai be released,” spokesman Johan Ndisi told AFP.