China has for the first time offered to include Taiwan officials in the "joint leadership" of a reunited nation, adding a new inducement to get talks started with the breakaway island government, according to a Hong Kong newspaper.

Since it began urging reunification talks in 1979, Peking has told Taipei's leaders they can maintain armed forces and their economic and social system as long as they call Taiwan a province of China and drop their flag and anthem.

A commentary last week in the Hong Kong News, however, suggested a new sweetener to attract a resistant Taipei. The paper, which is controlled by Chinese communists, quoted Vice Chairman Deng Xiaoping as saying recently, "it also is possible to have joint leadership."

"This means Taiwan's Nationalist Chinese Party cannot only cooperate, but also can jointly lead the country," explained the News, which often floats Peking proposals. "This expresses all the more something new."

Diplomatic analysts in Peking were uncertain what was meant by "joint leadership." An American diplomat said it could represent an offer to include Nationalist Chinese in the nation's State Council, which serves as a kind of cabinet running the government bureaucracy.

Despite their uncertainty, most foreign analysts viewed the new proposal as a significant step forward in Peking's efforts to assuage Taipei's fears of being engulfed by a poor communist nation with vastly different social and economic policies.

"It's a more daring and explicit offer than ever before," remarked a seasoned Western diplomat.

Another diplomatic observer believed the offer was aimed more at Washington than Taipei. He said the commentary showed Deng's commitment to regaining Taiwan by peaceful means in the hope that U.S. officials will do nothing to upset his plan by selling Taiwan the sophisticated weapons it has requested.

"The idea of joint leadership is not likely to go down well in Taiwan," said the analyst.

Since 1979 Taipei has consistently spurned the Chinese overtures, denouncing them as "united front tricks" designed to lull the prosperous island into a deal with its old communist foes that it would later regret.

Mainland officials claim that Taipei has grown more recalcitrant since the election of President Reagan, who gave the Nationalist Chinese hope during his campaign when he called for upgrading U.S. relations with Taiwan and for considering sales of new weapons.

Nevertheless, Peking authorities continue to chip away at Taiwan's reserve, offering to start gradual resumption of relations by establishing trade, postal and air service links that have been cut since the communists took over in 1949 and the Nationalist Chinese fled to Taiwan.

Elaborate preparations are now being made in China to celebrate Taiwan's national day Oct. 10. Marking this anniversary of China's 1911 revolt against the last dynasty underscores the common nationalism among Chinese on Taiwan and the mainland.

Although some communist officials have grown impatient with Taiwan's persistent cold shoulder, the dominant ruling faction headed by Vice Chairman Deng has urged a continuation of this "smile diplomacy" as the best strategy for obtaining early reunification.

Top Chinese policymakers are said to believe that chances for reunification remain better during the lifetime of Taiwan's President Chiang Ching-guo, now in his seventies and ailing from diabetes.

Despite his open hatred for communism, Chiang is known as an ardent Chinese Nationalist who hopes for reunification, albeit under non-communist rule. He also is seen as the strongest force against Taiwan's independence movement.

Peking officials are believed to fear that Chiang's death would remove the most powerful opponent to political forces seeking to obtain permanent status for Taiwan as an independent nation.

Communist leaders, who claim Taiwan is a province of the mainland, made clear in last week's newspaper commentary that independence for the island would be an intolerable development, which could force Peking to resort to armed attack.

That is the first time Peking is known to have threatened force as a response to Taiwan independence, reflecting Chinese communist fears of such a movement once Chiang departs.

Until last week's commentary, Peking officials have said they only would contemplate use of force against Taiwan if the Nationalist leaders indefinitely spurn peaceful reunification offers, ally with the Soviet Union against China or send Nationalist troops to attack the mainland.