Rio Tinto Group (ASX:RIO) has invested AU$150 million to purchase 100 iron ore rail cars, which will be locally manufactured in Western Australia, according to a Thursday statement.

The project, in partnership with Gemco Rail and CRRC Qiqihar Rolling Stock, has completed the construction of the first car, the filing said.

The rail cars will transport iron ore from Rio Tinto's Pilbara mines to its ports, the filing added.

Shares of the company fell 3% in recent Thursday trade.