An international human rights group says China poses a worldwide threat to human rights and is using its growing economic clout to silence its critics.

Human Rights Watch released its annual report. It reviews human rights practices in nearly 100 countries.

But it paid particular attention to China and condemned its treatment of Uighur Muslims.

Executive Director at Human Rights Watch Kenneth Roth said, "This is the most severe period of repression that we've seen in decades in China, probably going back to the Cultural Revolution or an era like that."

The group says China has built the most intrusive surveillance system it has ever seen in the Xinjiang Uygur Autonomous Region and coupled it with the largest case of mass arbitrary detention in decades.

The UN says more than a million Uighurs and other Muslims are being held there in government camps. China calls the camps ''vocational training centers.''

It has snapped back at past criticisms, calling the matter an internal affair.

The executive director of Human Rights Watch was expected to launch the report in Hong Kong. But he was denied entry there this week.

He said he thinks the reason is the Chinese government is terrified that what's happening in Hong Kong might spread to the mainland.

The territory has seen months of pro-democracy protests.

The report also noted that a growing number of countries that once could be relied on to promote human rights have largely abandoned the cause.

Japan's defense minister urged Beijing to work toward improving the situation regarding China's increasing maritime activities ahead of President Xi Jinping's planned spring visit to Japan.

Taro Kono made the call Tuesday during a speech at Washington-based think tank the Center for Strategic and International Studies.

He said Chinese government vessels violate Japanese territorial waters around the Senkaku Islands in the East China Sea three times a month on average. He also said they enter Japan's contiguous zone around the island on a daily basis.

Japan controls the Senkaku islands. The Japanese government maintains the islands are an inherent part of Japan's territory. China and Taiwan claim them.

Kono said Japan is concerned about China's continuous attempts to unilaterally change the status quo in the East China Sea, particularly around the Senkaku Islands, by forceful means. He added Japan cannot overlook such aggressive behavior.

He said that if China makes light of international norms, such as democracy and freedom, the country will have to pay the cost.

Kono also said Japan wants to extend a heartfelt welcome to Xi as a state guest this year. But, he said Beijing needs to work hard to improve the situation, otherwise, there may be a "difficult environment" for the visit.