Photo/IllutrationGui Minhai speaks in an interview on Chinese state broadcaster CCTV in 2016. (CCTV via The Asahi Shimbun)

STOCKHOLM/BEIJING--Beijing has doubled down in its criticism of Stockholm's support for Gui Minhai, a book publisher detained in China, after Sweden's minister for culture attended a literary award ceremony in his honour.

The Chinese ambassador to Sweden had threatened Minister of Culture Amanda Lind with a ban on entering China if she attended the prize-giving on Friday.

After the ceremony where Lind defended freedom of speech, China's embassy in Stockholm said in a statement on Saturday that Lind's attendance was a "serious mistake."

It did not reference the potential ban but warned that "wrong deeds will only meet with bad consequences."

"Giving an award to such a criminal is an outright political farce ... It also constitutes a gross interference in China's judicial sovereignty," the statement said.

Gui Minhai, a Chinese-born Swedish citizen, was abducted in Thailand in 2015 and is now detained in China. When based in Hong Kong, he published books critical of China's leaders, and the case has soured ties between Sweden and China.

Gui was briefly released in October 2017, but three months later he was seized by Chinese agents on a train bound for Beijing while in the presence of Swedish diplomats.

Svenska PEN, a literary organization awarded Gui the 2019 Tucholsky Prize, praising his work in the service of free speech. An empty chair symbolically represented the writer at the ceremony in Stockholm.

Sweden's foreign ministry said on Friday its view remained that China should release Gui and that it had contacted Chinese authorities over the ambassador's statements.

"It is not okay to interfere with what the Swedish government does," Foreign Minister Ann Linde said in an emailed statement to Reuters.

In a transcript of an interview given to Swedish radio on Friday by Chinese Ambassador Gui Congyou, the ambassador said Gui Minhai was being held on suspicion of revealing state secrets and intelligence on China, and denied allegations of torture.

The ambassador said Gui Minhai is not a persecuted author but a criminal who has "committed serious offences in both China and Sweden, and a lie-fabricator who viciously attacked the Chinese Government."