Gauck on Wednesday hit out at Communist rule in Soviet-dominated Eastern Europe, telling students that people could not be happy under a "dictatorship."

The German president, speaking to students at Shanghai's prestigious Tongji University, said social justice and rule of law were essential for a truly healthy society.

"Most people were neither happy nor liberated," he said of East Germany under Communist rule. "And the entire system lacked proper legitimacy.

"Free, equal and secret public elections were not held. The result was a lack of credibility, which went hand in hand with a culture of distrust between the rulers and those they ruled," he added.

Gauck claimed that the regimes of Eastern Europe had silenced their own people by locking them up and humiliating dissenters.

The 76-year-old, who lived under Communism in the former East Germany, also expressed concern about development within Chinese civil society, without giving specific examples.

"Vibrant and active civil society always means an innovative and flexible society," said Gauck.

UN urges Beijing to free dissidents

Last month, China rejected comments by UN rights chief Zeid Ra'ad Al Hussein that called for the immediate release of rights lawyers and activists. It followed some 250 arrests since July last year. Beijing said the remarks were "irresponsible."

Gauck has been urged domestically to pressure Beijing over human rights and freedom of speech. On Tuesday, he met five Chinese authors and literature professors in the converted former industrial park known as 798 Art Zone in Beijing, to discuss the role of literature in Chinese society.

Gauck told reporters that, during his visit, he has raised the situation of former DW journalist Gao Yu. The 71-year-old was in 2015 convicted of leaking state secrets and later freed. However, she has still been prevented from traveling to Germany, where she is seeking medical treatment.

The previous day, after meeting with his Chinese counterpart Xi Jinping and Chinese Prime Minister Li Keqiang, he held private talks in the German embassy with several prominent human rights lawyers and activists.

The German president is scheduled to visit the former imperial capital Xi'an before leaving China late on Thursday.

rc/jil (AFP, dpa)