MANILA, OCT. 28 -- Following weeks of racial tension, the Malaysian government has cracked down on its critics, arresting more than 70 opposition leaders and academics, closing three newspapers and banning public rallies, according to news reports from the Malaysian capital of Kuala Lumpur and telephone interviews today.

A police official in Kuala Lumpur told a news conference that 55 persons had been arrested, but by nightfall Chinese community leaders said the number had risen to 71. "The exercise of arresting people is ongoing," said one Chinese academic.

Most of those arrested are ethnic Chinese, who make up 32 percent of the country's 16 million population. They have charged that their rights are being eroded by indigenous ethnic Malays, who make up 48 percent of the population and control the country's politics under a power-sharing agreement with the Chinese and Indian minorities.

The arrests, under Malaysia's sweeping Internal Security Act, apparently began late yesterday with the detention of Lim Kit Siang, secretary general of the Chinese opposition Democratic Action Party.

{Prime Minister Mahathir Mohamad, in a special address to Parliament, said, "The situation has become very tense. Preventive action must be taken now to save the country from disastrous riots," United Press International reported from Kuala Lumpur. He banned rallies, including a meeting Sunday of his United Malays National Organization, the backbone of the 13-party ruling coalition.}

Prominent ethnic Malay critics of the government also were arrested, including members of a Moslem fundamentalist party who have advocated making Malaysia an Islamic state.

Under the Internal Security Act, persons deemed by authorities to be a threat to national security can be arrested and held without formal charges and without trial for renewable 60-day periods. The Malay government has treated public discussion of sensitive racial issues, or the questioning of ethnic Malay dominance, as a threat to national security.

Also arrested was an outspoken Chinese academic, Prof. Kua Kia Soong of the Malaysian Chinese Resource and Research Center. Kua recently published a collection of articles, mostly taken from the Chinese-owned, English-language daily The Star. The articles are critical of Malay cultural dominance.

The newspaper was ordered closed, along with another Chinese-language paper and a Malaysian biweekly, although it was unclear whether the papers were banned or only suspended.

The Star, which has been detailing charges of governmental corruption, is owned by the investment arm of the Malaysian Chinese Association, or MCA, the main Chinese political party within the ruling government coalition.

Haniff Omar, inspector general of police, reportedly compared the situation to May 13, 1969, when racial polarization erupted into rioting.

Racial harmony in Malaysia has been maintained for the past 18 years through the uneasy power-sharing arrangement. The Chinese and Indians essentially agreed to accept second-class citizenship in exchange for the preservation of their cultures and civil rights.

In the ruling coalition, the United Malays National Organization is allowed to select the prime minister, but the MCA remains a key coalition partner to represent Chinese interests.

The system has come under strain in recent months because of a growing challenge from the opposition Democratic Action Party to the MCA's longstanding claim to speak for Malaysia's Chinese.

Also, a series of moves by the Malay government, apparently aimed at making Malay the dominant culture, has offended the Chinese. Most of those moves have occurred in the areas of education and language, which are seen as the preserve of ethnic culture.

The most recent racial tension flared a few weeks ago with a controversial decision to send teachers who do not speak the Chinese dialect of Mandarin to senior posts in Chinese primary schools. That decision sparked unusual antigovernment street protests and a boycott of classes at several affected schools.

Then, on Oct. 18, an Army private went on a shooting spree in Kuala Lumpur's Chinatown area, killing a Malay and wounding several other Malays and Chinese.