The Australian Navy’s four Adelaide Class frigates have come out of their $1.5bn FFG upgrade programme, five years behind schedule.

The extended overhaul involved upgrades to the warships’ combat and fire control systems, air search radar, improved air defence and sonar and upgraded missile systems, according to The Australian.

The four warships – HMAS Sydney, HMAS Melbourne, HMAS Darwin and HMAS Newcastle – entered the upgrade programme under a $1.5bn contract that had been put out of action for many years, according to the prime contractor Thales.

Defence Minister John Faulkner said when the current government was elected this upgrade project was over four and a half years behind schedule with serious concerns about whether it was even achievable.

“These delays resulted from a significant underestimation of the complexity of the upgrade task at project inception in the late 1990s,” he said.

Thales Australia managing director Chris Jenkins said the FFG upgrade programme was the most sophisticated and complex naval systems integration project ever undertaken in Australia.