TAIPEI (Reuters) -Taiwan's defence ministry said on Friday it was aiming for delivery of the first new F-16V fighter jets by the end of this year, blaming "acute fluctuations" in the international situation for delays in the island receiving them.

The United States in 2019 approved an $8 billion sale of Lockheed Martin F-16 fighter jets to Taiwan, a deal that would take the island's F-16 fleet to more than 200 jets, the largest in Asia, to strengthen its defences in the face of a stepped up threat from China, which views Taiwan as its own.

Taiwan has been converting 141 F-16A/B jets into the F-16V type and has ordered 66 new F-16Vs, which have advanced avionics, weapons and radar systems to better face down the Chinese air force, including its J-20 stealth fighter.

But Taiwan has complained of delays for the new F-16Vs, saying problems include software issues.

In an update on the deliveries, Taiwan's defence ministry said the first batch of new F-16Vs was meant to have been sent in the third quarter of this year.

"Because of acute fluctuations in the international situation, which have resulted in a compound impact such as delays in deliveries of some suppliers and adjustments to the U.S. assembly schedule, there has been a partial adjustment in when they will leave the factory," it said in a statement.

The ministry will "strive to complete the shipment of the first aircraft in the fourth quarter".

The air force will keep a close watch on the production schedule and make factory visits with the aim to have the deliveries completed by the end of 2026, it added.

Lockheed Martin told Reuters it was "grateful for the trust Taiwan has placed in us across its F-16 programmes".

"In partnership with the U.S. government, Lockheed Martin is focused on developing F-16 capabilities," it added.

The U.S. State Department said long delivery dates were not a Taiwan-specific challenge.

"The U.S. government is actively reviewing our policies and processes to ensure that we move arms sales cases as quickly as possible, particularly for Taiwan," it said in a statement.

Taiwan has reported delays to U.S. weapons deliveries such as Stinger anti-aircraft missiles since 2022, as manufacturers give supplies to Ukraine to help it battle Russian forces, and the issue has concerned U.S. lawmakers.

Taiwan's air force is well-trained but some of its fighter jets are aging, including its French-made fleet of Mirage 2000s first received in 1997. One crashed into the sea this week during a training exercise.

The air force has repeatedly scrambled to see off Chinese military aircraft flying near the island in the past five years.

Taiwan's government rejects China's sovereignty claims.