Canadian plane and train manufacturer Bombardier Inc has signed a US$1.14 billion contract to supply passenger trains to the two new operators of Britain's South Western rail franchise.

Bombardier Transportation will sell and maintain 750 Bombardier Aventra rail carriages to Britain's FirstGroup and Hong Kong's MTR Corp.

FirstGroup, also operator of the Great Western franchise, will run the Southern Western franchise - trains to London from cities such as Bristol and Exeter - along with MTR from August 20.

Bombardier will also enter a technical services and spares supply agreement for the duration of the seven-year franchise, with an option to extend it later, it said.

Bombardier and Siemens have been identified in recent media reports as holding talks to unite their rail operations, although such a tie-up would be difficult because of anti-trust concerns and questions over which company would retain control of the combined venture.