WASHINGTON—The Bush administration announced plans Friday to sell up to $6.5 billion in arms to Taiwan, a decision sure to anger Taiwan’s rival China and one that could complicate stalled North Korean disarmament efforts.

The announcement of the package, which includes Apache helicopters and Patriot III missiles, came in a notification to Congress posted on the Defense Security Cooperation Agency Web site. The State Department said lawmakers, who were expected to leave Washington on Friday to campaign for November elections, have 30 days to comment on the proposed sale. Without objections, the deal would proceed.

The arms package enjoys support among senior lawmakers, who were briefed on the deal by administration officials. China, however, vehemently opposes the provision of weapons to Taiwan, which Beijing claims as its territory and has threatened to invade should the self-governing island ever formalize its de facto independence.

U.S. arms sales to Taiwan are a sensitive matter because any dispute between China and Taiwan could ensnare the United States, Taiwan’s most important ally and largest arms supplier.

The United States and China are part of troubled six-nation negotiations to persuade North Korea to abandon its nuclear weapons. A successful result to the stalled talks is an important foreign policy goal of the Bush administration in its remaining months in office. China, which hosts the talks, is seen as having economic and political leverage with the North.

The State Department said in a statement that the arms package, which also includes Harpoon missiles, Javelin missiles, upgrades for Taiwan’s E-2T aircraft and spare parts for Taiwan’s air force, is “a significant and tangible demonstration of the commitment of this administration to provide Taiwan the defensive arms its needs to be strong.”

Rep. Ileana Ros-Lehtinen, the senior Republican on the House Foreign Affairs Committee, said judicious arms sales constitute “an essential element of United States support for a secure, stable and democratic Taiwan, as well as peace and stability across the Taiwan Strait. Now is not the time to backtrack from that historic and bipartisan policy.”

This year’s U.S. Defense Department report on China’s military said Beijing continues its huge military buildup opposite Taiwan, further pushing the balance of power between the two rivals toward the mainland’s favor.

Taiwan relies on U.S. weapons to keep pace with China. Washington shifted its recognition as China’s official government from Taipei to Beijing in 1979, but it remains committed to Taiwan’s defense and has hinted it could come to the island’s aid if China should attack.

U.S. caution about selling arms to Taiwan reflects China’s growing economic and political clout.

The Bush administration needs China’s help in a host of international efforts, including attempts to confront Iranian and North Korean nuclear programs.

Among the principal contractors for the Apache sales are Boeing Co., General Electric Co. and Lockheed Martin Corp. For the Patriot missiles, the principal contractors are Raytheon Co. and Lockheed Martin.