The Royal New Zealand Navy Anzac frigate, HMNZS Te Mana, has rejoined the fleet after undergoing a multi-million dollar upgrade.

HMNZS Te Mana is one of two frigates that has undergone a seven-month refit, which has seen new diesel engines installed to improve performance and reduce fuel costs.

The new engines, costing about $57m for both ships, will not allow the ships to go faster than their top speed, making the ships more economic to operate.

The refit includes replacement of ship’s auxiliary generators, installation of a new communications and control system and a modernised $25m Phalanx gun system.

The 118m-long ship has a standard displacement capacity of 3,600t, can cruise at a speed of 27kt and carries one KAMAN SH-2G Super Seasprite helicopter armed with torpedoes, depth charges and Maverick missiles.

Te Mana is expected to remain in service until at least 2025, according to The New Zealand Herald.