China today warned that U.S. plans to continue military sales to Taiwan have driven Sino-American relations to a crisis point, making a solution of the issue "imperative" before the two nations can develop or even maintain their contacts.

In a commentary, the Communist Party newspaper People's Daily said the weapons sales infringe on China's sovereignty, block its efforts to reunify with Taiwan and show an American failure to "honor its commitment" to respect Chinese territorial integrity.

"It's a firm and authoritative statement of their position," said a Western diplomatic analyst.

"It is a reminder that the Chinese mean business on this issue.

"It shouldn't be taken lightly."

The People's Daily article spells out in emphatic terms Peking's position on the arms issue amid reports that the Reagan administration is nearing a decision on the sale of an advanced fighter plane to Taiwan. There have been reports that Chinese officials have warned Washington that such a sale would lead them to downgrade relations with the United States. In January Peking directed the Netherlands to reduce its mission to the level of a charge d'affaires when that country sold two submarines to Taiwan.

Although the commentary avoided specific mention of U.S. plans announced this week to supply Taiwan with at least $25 million in spare parts, it noted that recent news from Washington makes the arms sales issue "more serious."

The commentary said such behavior raises questions of true U.S. intentions for "China's territory of Taiwan" and suggests "hegemonism," a code word previously reserved to describe the domineering foreign policy of China's archenemy, the Soviet Union.

"Now, we must state explicitly that if the United States desires to preserve and develop its relations with China," said People's Daily, "it must seek, on the basis of genuine respect for China's sovereignty, a solution to the issue of selling arms to Taiwan.

"There is no other way."

The article was signed by "the paper's commentator," which means it reflects the views of the party's top leadership. It is seen as the sharpest and most explicit public airing of China's stance on the issue.

The issue has simmered below the surface of Sino-American relations ever since Washington shifted its recognition in 1979 from Taipei to Peking, ending 30 years of hostility toward the communist mainland.

The U.S. side agreed to consider Taiwan as a part of China, but it reserved the right to maintain "unofficial" ties with the estranged island and continue to supply it defensive arms.

China bitterly rejected the plan but "agreed to disagree" and went ahead with normalization. The issue largely remained dormant until President Reagan raised it during his 1980 campaign.

After Reagan entered office and held out the possibility of selling Taiwan a new advanced fighter, the Chinese stepped up their attack, further intensifying it since September when Peking offered Taipei new incentives to reunify.

In today's People's Daily, the commentator noted China's "unremitting efforts" to achieve peaceful unification with Taiwan, arguing that Peking has "created conditions most favorable to ending U.S. arms sales to Taiwan . . . and whatever threatens the relations between the two countries."

Nevertheless, said the commentator, Washington continues to sell arms to the breakaway island--at an estimated rate of $700 million to $800 million annually--prompting questions about America's motives.

"Is it not hegemonism for the United States to flout criteria governing international relations by encroaching upon the sovereignty of another country and interfering in its internal affairs?"

What China now demands of the United States, according to People's Daily, is "genuine respect" for the nation's sovereignty on the Taiwan issue--a requirement for which there will be no "unprincipled accommodation."

After fighting for their independence over the past 100 years, the commentator pointed out, the Chinese people "have stood up today and will in no case tolerate any attempt of any foreign country to infringe upon their national sovereignty, divide their territory and interfere in their internal affairs."

Not only has Washington failed to live up to its obligations stated in the normalization pact to respect China's sovereignty. It also has "resorted to various prevarications to absolve itself of its own commitment," the newspaper said.

The commentator apparently was referring to the Taiwan Relations Act, which was passed by the U.S. Congress after Sino-American normalization and authorizes U.S. arms sales to Taiwan to insure its defense.

Contending that China has been "reasonable" in handling the contentious military sales issue, the commentator said that once Washington accepts "the fundamental principle" of refraining from Taiwan arms supplies, then the two sides "may negotiate ways and means of settling this issue."

"This is a severe test for the United States government, which will show whether or not it truly treasures its relations with China."