While Washington does not have official diplomatic relations with Taipei, it remains the island's most important backer and biggest arms supplier.

The proposed sale of the F-16 and radar system parts consists of equipment in existing US military stocks and was worth an estimated $320 million, the Defense Security Cooperation Agency said in a statement, with deliveries estimated to start in 2025.

"This proposed sale serves US 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 DSCA said.

"The proposed sale will improve the recipient's ability to meet current and future threats by maintaining the operational readiness of the recipient's fleet of F-16 aircraft."

A separate sale involving follow-on support and equipment for a tactical communications system was worth $65 million, the DSCA said.

The deals were approved by the State Department, with the DSCA providing the required notification to Congress on Friday.

China insists self-ruled Taiwan is part of its territory and has long opposed US arms sales to the island.

The sales were announced as Taiwan's President Lai Ching-te was due to leave on Saturday for a trip to three Pacific island allies, with stopovers in Hawaii and the US territory of Guam.

Taiwan's defense ministry on Saturday "expressed gratitude" for the latest arms sales.

The items "will help maintain the combat readiness of the Air Force's F-16 aircraft equipment and bolster our air defense," the ministry said in a statement.

"Taiwan and the United States will continue to consolidate our security partnership."

The foreign ministry said it was the 18th time that President Joe Biden's administration had announced arms sales to the island.

Taiwan was determined to strengthen its defences in the face of China's military pressure and "grey zone harassment," it said in a statement, referring to tactics that fall short of an act of war.

China has ramped up military pressure on Taiwan in recent years with near-daily deployments of fighter jets and warships around the island.

On Saturday, Taiwan's defense ministry said 18 Chinese military aircraft and seven naval vessels as well as two balloons were detected in the 24 hours to 6:00 am (2200 GMT Friday).