The Chinese cities of Beijing and Hong Kong were the scenes Saturday of demonstrations to mark the 22nd anniversary of the bloody Tiananmen Square crackdown during which hundreds, perhaps thousands, died.

It was on June 4, 1989, when the Chinese government sent tanks and soldiers into the square in central Beijing, the Chinese capital, to crush weeks of pro-democracy demonstrations.

The anniversary is being marked in the midst of another Chinese government crackdown, this one against activists, lawyers, writers and bloggers.

The U.S. State Department has been joined by the government in Taiwan in calling on China to release jailed dissidents and account for those killed, detained or missing in the Tiananmen Square crackdown. But a Chinese foreign ministry spokesman insisted the matter is closed.

The group Chinese Human Rights Defenders said Saturday that security officers took former government official Bao Tong to an unknown location this week. And the Information Center for Human Rights and Democracy said liberal intellectual Chen Ziming and many others have been placed under house arrest.