Taiwan will this week receive its first batch of a fleet of Indigenous Defensive Fighters upgraded as part as part of a $587 million dollar project to beef up air defences, officials said Sunday.

An unspecified number of the domestically-manufactured jets are scheduled to be delivered in central Taichung city Thursday, an air force spokesman said.

The defence ministry is spending Tw$17 billion (US$587 million) upgrading 71 IDFs, or nearly half of the fleet based in the southern Tainan air base, as part of a four-year project which began in 2009.

“The rest of IDFs may or may not be upgraded, contingent upon our future budget,” the spokesman told AFP.

The retro-fitted jet will be armed with four locally made air-to-air missiles, up from two, and ground attack bombs and missiles, experts say, adding that its radar, electronic fighting system and mission computer have also been enhanced.

The air force had been reluctant to give the green light to the project, first presented by the island’s sole aircraft-maker Aerospace Industrial Development Corp in the early 2000s, experts said.

But Taiwan fast-tracked the upgrade in 2008 after the United States refused to sell the island F16C/D jets or upgrade its F16A/Bs.

Taiwan’s President Ma Ying-jeou, the architect warming ties with Beijing over the past three years, renewed his call on the United States to sell F-16C/Ds while meeting visiting Paul Wolfowitz, a former US deputy secretary of defence, in Taipei Saturday.

The United States last year approved $6.4 billion in weapons for Taiwan, including Patriot missiles and Black Hawk helicopters. But the package did not include fighter jets, which Taiwan believes are necessary to close the gap as China rapidly boosts its military budget.

China angrily protested the package, temporarily cutting defence ties with the United States. Beijing considers Taiwan — where the mainland’s defeated nationalists fled in 1949 — to be a territory awaiting reunification.