TAIPEI, Taiwan >> Taiwan is postponing purchases of U.S.-made Black Hawk helicopters and Patriot air defense systems that are part of a $6.4 billion U.S. weapons package that has been strongly opposed by China, officials said Tuesday.

A lawmaker said the delay was caused by budgetary shortfalls, while the Defense Ministry blamed it on manufacturing delays.

Lin Yu-fang, a ruling Nationalist Party lawmaker on the legislature’s defense committee, said the government is either delaying purchases of new items or postponing payments for existing programs because of the funding shortfall. The procurement of six Patriot missile systems has been pushed back from 2014 to 2017 and 60 Black Hawk helicopters from 2016 to 2019 or 2020, he said.

Defense Ministry spokesman Luo Shou-he denied that the postponements were caused by budget constraints and instead cited production delays by U.S. defense contractors.

Taiwan’s Patriot air defense systems are being made by Lockheed Martin Corp., while Black Hawk helicopters are produced by Sikorsky Aircraft Corp.

No immediate comment was available from either company before U.S. office hours Tuesday.

The U.S. remains Taiwan’s most important strategic partner and is required by law to provide it with defensive weapons.

Last year, the Obama administration notified Congress it was making $6.4 billion in weapons available to Taiwan, including missiles, Black Hawk helicopters, information distribution systems and two Osprey Class mine hunting ships.

American arms sales to Taiwan are strongly opposed by China, which sees them as interference in its domestic affairs and says they undermine ties between Beijing and Washington.

Senior Taiwanese officials have expressed concern that budgetary shortfalls amounting to several billion dollars are causing the government to struggle to meet a plan to turn the military into an all-volunteer service by 2015.

Taiwan has an annual defense budget of $12.92 billion, while China is spending $92.57 billion on its military this year.

China claims that Taiwan is part of its territory, although the two sides split during a civil war in 1949. Beijing is determined to unify with Taiwan, by force if necessary.