BERLIN China's ambassador to Germany was summoned to the office of Foreign Minister Guido Westerwelle on Wednesday for a meeting about detained Chinese artist-activist Ai Weiwei.
"The artist Ai Weiwei must be released," Westerwelle told a news conference.
"We clearly back freedom of artistic expression and free speech. That's why we'll have the Chinese ambassador at the foreign ministry for a meeting to clearly express this view."
Ai, 53, has not been in contact with his family since Sunday and his mobile phone remained off on Wednesday morning.
It appears Ai, a combative critic of the ruling Communist Party and a well-known contemporary artist, has joined a list of dozens of dissidents and activists put in detention or informal custody recently.
Officials and police have made no comment on his case.
The United States, Britain, Germany and other governments have already denounced Ai's detention and China's growing use of extra-judicial detentions against dissidents.
(Reporting by Oliver Denzer; writing by Erik Kirschbaum; editing by Matthew Jones)