Communist China's top leader has pledged to give Taiwan authorities an "equal footing" in running the nation once they agree to reincorporate the breakaway island, the state-run news agency reported tonight.

The pledge by Deng Xiaoping appears to amplify Peking's two-year-old offer to assign Nationalist Chinese officials on Taiwan an unspecified leadership role in a reunified country and to guarantee their right to retain the island's capitalist economy and armed forces.

Nationalist leaders who fled the mainland after the communist takeover in 1949 have rejected the offer as a trick to lull them into a deal that would at best render them powerless provincial officials.

Deng, in remarks reportedly made June 18 to foreign scientists visiting Peking, stressed that the communist regime intends to share power with its old foes, not destroy them.

"Such cooperation, in the first place, means cooperation and consultation on an equal footing," Deng said. "It is not consultation between the central government and a local government but between two parties."

The overture is unlikely to attract support among Nationalist officials, who have called on Peking to renounce communism as a condition for reunification.

Published a month after the remarks were made, the appeal is believed at least partly aimed at the Reagan administration, which approved a $530 million arms sales package to Taiwan last week.

Peking, which has not specifically responded to the latest weapons deal, contends that U.S. arms sales to Taiwan strengthen the Nationalists' resolve to reject communist peace offers. It calls the Reagan administration hypocritical for at once urging peaceful reunification of the island and selling arms to Taipei.

Foreign analysts said Deng's remarks apparently were reprinted tonight in part to give further evidence of Peking's peaceful intentions and the futility of new U.S. arms sales.

Deng, who heads China's powerful military and controls the Politburo's elite standing committee, said Peking is so anxious to achieve national unity it is willing to "give full consideration to terms that Taiwan can accept."

"We cannot engage in empty talk," the Chinese leader said. "Our country needs reunification, without which it will have no hope."

Deng's urgent tone reflects the fears of China's aged communist hierarchy that the prospects for reunification greatly dim as they and their Nationalist contemporaries in Taipei give way to a younger generation that may have less personal commitment to a unified country.

"People like me are getting old," Deng, 79, said. "Our descendants will remember us if we accomplish this cause left over by our predecessors. If we fail to achieve it, our descendants will blame us when they write the country's history."

He said there are "favorable conditions" for achieving this historical task today, apparently referring to the accommodating stance of his regime.

Peking initiated its peace plan in 1979, retreating from 30 years of bellicose threats to "liberate" Taiwan by force.

After two years of proposing personal and commercial exchanges to smooth the way for eventual reunification talks, Peking dramatically stepped up its campaign in September 1981 by offering to include Nationalist officials in the leadership of a reunited nation.

In his recent remarks, Deng emphasized that policy toward the island of 18 million people would not change after it was brought back to the fold.