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 American call was a gross intervention in China's internal affairs and a groundless accusation of the Chinese government.

In a State Department release Sunday, deputy spokesman Mark Toner said the United States also wants China to provide a full accounting of all of those killed, detained or missing during the violent suppression of the demonstrations. It also called for an end to what it described as the continued harassment of participants in the protests and their families.

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.