The US framed the sale as a mutually beneficial transaction.

"This proposed sale serves U.S. national, economic, and security interests by supporting the recipient's continuing efforts to modernize its armed forces and to maintain a credible defensive capability," the State Department said.

The sale "will help improve the security of the recipient and assist in maintaining political stability, military balance, and economic progress in the region," the statement added, a reference to Washington's strategic priority of countering Beijing's influence.

The MK-48 torpedoes -- which can be launched from a submarine -- are being provided from existing US Navy stock, the State Department said.

Taiwan has been ruled separately from the mainland since 1949 after the Nationalists lost a civil war to the Communists and fled to the island to set up a rival government.

Beijing however views Taiwan as part of its territory and has vowed to seize it by force if necessary.

Washington severed diplomatic ties with Taipei in 1979 in order to recognize the government in Beijing as China's only legitimate ruling body, but remains Taiwan's main weapons supplier.

President Donald Trump has made it clear he will continue the practice.

China recently told France that a weapons deal with Taiwan would damage French-Chinese relations.

The deal is related to the 1990s sale of French warships to Taiwan, according to the Taiwanese press, which at the time led to a diplomatic crisis between Paris and Beijing.