West Australian shipbuilding company Austal has won a $434 million contract to build two more Expeditionary Fast Transport catamarans for the US Navy.

Austal already has a 10-ship contract with the US navy and has delivered seven of them.

It brings the value of the deal to $2.5 billion and allows the Henderson-based company to extend its US production schedule to 2022.

Austal chief executive officer David Singleton said the new deal reflected the US Navy’s ”continued confidence and investment in a proven product”.

The 103m vessels can travel at 35 knots and carry up to 300 passengers.