SEOUL, July 18 (Reuters) - South Korea's Joint Chiefs of Staff endorsed a plan on Friday for the country to design its own mid-level fighter jet, which a state think tank estimated will cost up to 8.5 trillion won ($8.24 billion) to develop.
Dubbed the KF-X programme, the fighter jet is expected to be built by the country's sole jet builder, Korea Aerospace Industries Ltd (KAI), after being co-developed with Lockheed Martin Corp, two people with direct knowledge of the matter said.
The Joint Chiefs said in a statement that they had endorsed a twin-engine fighter jet to be developed for delivery starting in 2025.
KAI makes the T-50 family of jets, South Korea's first home-built light trainer and fighter, which was co-developed by Lockheed Martin. South Korea is also buying F-35 fighters from Lockheed Martin.
KAI sold 12 T-50 variants to the Philippines for around $420 million in March, after previously exporting the jets to Iraq and Indonesia.
South Korea's acquisition of 40 Lockheed Martin F-35 fighter jets for around 7.34 trillion won is expected to be finalised in the third quarter. The deal's accompanying offset offer includes Lockheed Martin involvement in the KF-X programme, the people said.
However, the scope of Lockheed Martin's involvement in the programme is still being negotiated, the people added.
Indonesia also participated in earlier studies of the KF-X programme and remains a potential partner, one of the people said.
State-run think tank Korea Institute for Defense Analyses (KIDA) reported earlier this month that a twin-engine version of the fighter jet is expected to cost around 8.5 trillion won, the person told Reuters.
Both sources declined to be identified as details of defense requirements are confidential. Officials with Lockheed Martin could not be reached for comment.
KAI referred questions to the country's arms procurement agency, the Defense Acquisition Program Administration (DAPA), as companies have yet to be named for the programme. DAPA referred questions to the Joint Chiefs, who reiterated their statement.
$1 = 1,031.60 Korean won Reporting by Joyce Lee; Editing by Matt Driskill