The award is a blow to defence services company Science Applications International Corp, which was competing to be lead contractor on the vehicle.

The Department of Defence estimated that procurement and maintenance of all 208 vehicles in the programme will be about $6.2 billion over their lifetime.

The new vehicles will replace the ageing fleet of expensive-to-maintain flat-bottomed amphibious assault vehicles in service since 1972.

BAE confirmed the $198 million deal in a statement and said the company has already produced 16 prototypes. A U.S. official and a person familiar with the decision earlier told Reuters that BAE had been awarded the deal.

SAIC said it was "disappointed" that its vehicle was not selected.

The award for an initial batch of 30 vehicles shifts the programme from the prototype and testing phase into low-rate production, which is scheduled to begin this year.

A recent report by the U.S. Government Accountability Office cautioned the Marine Corps from entering a second year of low-rate production until the contractor demonstrates the vehicles produced have consistently high quality manufacturing standards.

The acquisition cost for the 208 vehicles is expected to total about $1.2 billion, sources said.

Costs per vehicle would ease in the early 2020's if the Marines elect to continue production past 208.

BAE Systems partnered with Italian company Iveco Defence Vehicles to build its ACV offering.

In 2011, the Marines started a competition for the next generation of ACVs.

In 2015, it awarded SAIC and BAE development and testing contracts for the wheeled amphibious combat project.

The programme will be a replacement for the tracked Expeditionary Fighting Vehicle (EVF) that was being developed for the Marines by General Dynamics Co before its cancellation in 2011 following large cost increases and technical issues.

The Marine Corps spent $3.7 billion on development before cancelling the EVF programme.

(Reporting by Idrees Ali and Mike Stone in Washington; Editing by Bill Berkrot and Leslie Adler)

By Idrees Ali and Mike Stone