The news was confirmed by the president of Hitachi Power Tools, Katsumi Nagasawa, who said the move would not affect its relationship with rival bidder GE. Hitachi and GE are closely aligned in the nuclear sector.
According to reports in the Japanese press, MHI and Hitachi could offer JPY 500 billion ($4.9 billion) for Alstom's steam turbine business.
This would leave Siemens to pay the same figure for the gas turbine division. There was no mention of what would happen to the wind division, leaving further credence to the rumour that Areva would be prepared to step in to acquire Alstom Wind.
Yesterday, Mitsubishi Heavy Industries (MHI) has announced it was considering a joint bid with Siemens to acquire Alstom Energy.
In a statement, MHI and Siemens said the companies are currently evaluating a potential proposal, with a view to presenting it to Alstom on 16 June.
Alstom has a deadline of 23 June to respond to GE's own EUR 12.35 billion bid for Alstom's energy. The deadline was extended following a request from the French government.