China's foreign ministry has expressed “strong dissatisfaction” with a U.S. call for Beijing to free all those still imprisoned for the 1989 Tiananmen Square demonstrations.

Responding to a question from the VOA Mandarin service, foreign ministry spokesman Liu Weimin told reporters that the U.S. State Department call was a gross intervention in China's internal affairs and a groundless accusation against the Chinese government.

“I knew you would ask this question for sure. There has been a clear conclusion by the Chinese government and party over that incident. Over the past more than 20 years China has witnessed continuous economic development, democracy and rule of law and prosperous cultural programs. All this is reflecting the common aspiration of the Chinese people. The statement you mentioned is released by the U.S. side year after year in disrespect of facts. It is a gross intervention in China's internal affairs and groundless accusation of the Chinese government. China expresses it's strong dissatisfaction and firm opposition to that.”

The Chinese rebuttal comes as tens of thousands of people in Hong Kong gathered for a candlelight vigil marking the 23rd anniversary of the Tiananmen Square protests and the deadly government crackdown that followed.

On June 4, 1989, Chinese troops, backed by tanks, moved in to crush a student-led demonstration centered in Beijing's Tiananmen Square. The crackdown triggered worldwide condemnation, with estimates of those killed ranging from several hundred to several thousand people.

China still considers the incident a “counter-revolutionary rebellion” and has never admitted any wrongdoing in its handling of the uprising. The topic is banned from state media and, although the subject is taboo in China, some activists have gathered to mark the anniversary.

Meanwhile, Chinese microblogs buzzed with conspiracy theories Monday, after censors moved to block access to Shanghai's benchmark stock index. The censoring occurred after stocks closed 64.89 points lower, matching, in apparent coincidence, the calendar numbers for the June 4, 1989 crackdown.