Emirates Airline is boosting capacity on two trans-Tasman routes by using bigger aircraft from August 2.

On the Auckland to Melbourne to Dubai route and the Auckland-Brisbane-Dubai route, Emirates will replace the current Airbus A340-500 aircraft currently being used with a Boeing 777-300ER aircraft. The change means an extra 672 seats per week being available in each direction.

Emirates' other Auckland service, via Sydney to Dubai, is operated by an Airbus A380 superjumbo.

The Boeing 777-300ER will operate in a three-class configuration with eight first class, 42 business class and 304 economy class seats. The aircraft type already operates on Emirates' daily service out of Christchurch.

The Airbus A340 is typically configured with about 316 seats in a three-class conifguration.