US arms sales to Taiwan hurt China’s national security, its foreign minister said, escalating the rhetoric in a dispute threatening to deepen rifts between the world’s biggest and third- biggest economies.

Foreign Minister Yang Jiechi was the latest and most senior official to denounce the arms sale plan Washington announced on Friday. The Obama administration has defended the package worth about $ 6.4 billion as necessary to boost regional security.

Yang, traveling in Cyprus, said China and the United States had held many discussions about the arms sales, but Washington had ignored Bei - jing’s demand they be stopped, the official Xinhua news agency reported yesterday.

The United States should « truly respect China’s core interests and major concerns, and immediately rescind the mistaken decision ... in order to avoid damaging broader China- US relations, » Yang said.

He said the US move had « damaged China’s national security and great task of reunification ( with Taiwan). » Beijing considers Taiwan a breakaway province.

Reflecting the intense emotions over the issue, Chinese Internet users vented anger with calls to boycott top US exporter Boeing and other firms involved in the sales.

China has for years opposed US arms sales to Taiwan. For the first time, however, Beijing is seeking to pressure the United States by punishing those private companies whose arms are involved in the Taiwan sales.

China said it would impose unspecified sanctions on the companies and reduce international cooperation with the United States unless it canceled the new arms package.

Beijing planned to postpone or partially halt some military cooperation, including a series of visits planned for this year, among them US Defense Secre tary Robert Gates’s planned trip to China, meetings between top military commanders, and mu tual visits by naval ships, Xinhua reported.

« Especially at a time when the world has yet to escape the financial crisis, and also faces global problems such as climate change, food security and nuclear nonproliferation, it is not in US interests for China- US relations to experience setbacks, » the state news agency said. US officials sought to downplay the dispute on Saturday.

« We regret that the Chinese government has announced that it plans to curtail military- to- military and other security- related ex - changes and take action against US firms, » said P. J. Crowley, the State Department’s chief spokesman.

« We believe our policy contributes to stability and security in the region, » he said.

US officials have said Tai - wan, which lags China in the balance of military power, needs updated weapons to give it more sway when negotiating with Beijing, which Taiwan says has aimed more than 1,400 shortrange and mid- range missiles at the island.

Since 1949 when Na tio - nalist forces fled to the island after losing the mainland to Communist rebels, Beijing has demanded Taiwan accept unification, threatening to use force if necessary. Andrew Yang, De puty Minister of Taiwan’s Ministry of National Defense, described the sale as involving defensive weapons that could help prevent cross- Strait hostilities.

« This is very much about enhancing Taiwan’s self- defense to fend off any attack from Beijing.

Beijing will think twice. That’s why they are opposing US arms sales, » he told Reuters . The China- US rift comes despite improving mainland- Taiwan economic cooperation, and the thrust of Beijing’s fury has been directed at Washington rather than at Taipei.

The sales, subject to congressional review, include Black Hawk utility helicopters built by United Technologies Corp’s Sikorsky Aircraft; Lockheed Martin Corp- built and Ray - theon Co.- integrated Patriot missile defenses; and Harpoon land- and sea- attack missiles built by Boeing Co.

The Global Times , a popular Chinese newspaper with a nationalist slant, and a Chi - nese web portal, Sohu, launched an online petition protesting the sales.

It brought calls for boycotts of US goods and bitter denunciations of the United States.

« All the people together boycott US goods!, » said one comment left on the petition website.

But a sampling of residents in Beijing showed little enthusiasm for a boycott.

« A boycott is not at all feasible.

We have an open economy now.

So many US companies are in China that if you stop buying their goods you’ll also end up hurting Chinese people, » said Ken Zheng, a 23- year- old consultant who stood outside an outlet of US- based fried chicken chain KFC in Beijing’s fashionable Sanlitun area.

« A couple of years ago people called for a boycott of Japanese goods, but that soon fizzled out, and the political temperature was much hotter then, » he added.

Connie Zhang, also outside the KFC, said: « What a silly idea.

Who on earth would suggest such a thing? I’m only interested in peace. I want nothing to do with politics, » she added.

Representatives of the companies involved in the arm sales either had no immediate comment or did not respond to calls.

Boeing has big commercial interests in China, the world’s most populous market, including commercial aircraft sales.

United Technologies also has significant business in China, where it sells Carrier brand heating and air- conditioning, Otis elevators and escalators and other products.

The other arms makers appear to have less China exposure.

Although they cooperate on counter- terrorism, nuclear arms control, climate change and other issues, Beijing and Washington are at odds over trade, China’s tight control of its currency, policies in Tibet and Internet censorship.

The feud could damage broader diplomacy between the two permanent members of the UN Security Council. Washing - ton has sought China’s backing in its nuclear standoffs with Iran and North Korea and in fighting climate change, and is preparing for a world summit on nuclear weapons in April.