Berlin had urged Beijing in recent days to let Liu leave China for treatment abroad, possibly in Germany. Foreign Minister Sigmar Gabriel said Thursday he "deeply regrets" that China didn't let Liu and his wife, Liu Xia, travel to Germany.
He urged China to lift restrictions on Liu Xia's movements and communications and added, "She and her brother, Liu Hui, should immediately be allowed to leave for Germany or another country of their choice if they wish to."
Gabriel also urged China to look in a "credible and transparent way" into whether Liu Xiaobo's illness could and should have been detected earlier.
Liu was transferred to a hospital after being diagnosed with advanced liver cancer in prison in May but remained under police custody.