China has stepped up its criticism of a proposal by Japan, India, Brazil and Germany to become permanent members of the U.N. Security Council. 

The four nations, known now as the G-4, have ignited anger among Chinese officials, who oppose Japan's bid to join the Security Council. China contends Japan must first meet Beijing's nonspecific demands for redress for atrocities committed by Japanese occupation forces in China during the first half of the 20th century.

Chinese Foreign Ministry spokesman Liu Jianchao, at a regular briefing Tuesday, called the proposal "dangerous."

Mr. Liu said the four nations hastily came up with the proposal and are trying to put it up for a vote. The official calls the move detrimental to solidarity among U.N. members, and he says it hurts the interest of developing countries.

China supports another plan proposed by Italy, Mexico, and Pakistan to expand the body by ten more members - six of them permanent.

Beijing's criticism of the G-4 plan comes after Chinese U.N. Ambassador Wang Guangya said last week that China would block any move to give Japan, India, Brazil, and Germany permanent seats on an enlarged security council.

Tensions between China and Japan have been high over the past few months. In April, the Chinese government allowed thousands to take to the streets to protest some Japanese history textbooks that China says whitewash Japan's past record of aggression.

Beijing banned the protests after some of the demonstrations turned violent. Relations suffered further last month when Japan's prime minister defended his visits to a controversial war shrine in Tokyo where convicted war criminals are among those honored.

A proposal to expand the U.N. Security Council would require approval by two-thirds of the 191 United Nations members.

Japan says it will continue working to convince China to vote for the G-4 plan. Japan's foreign minister on Tuesday began a five-day tour of Brunei, Cambodia, and Vietnam in an effort to build support for the proposal.

The United States has already made clear its support for Japan's candidacy for a permanent Security Council seat.