document: They have increased the cash component of their bid by 1.2bn euros to 8.2bn euros (Â£6.6bn; $11.2bn).
  The improved offer raises the valuation of Alstom's energy business by 400m euros to 14.6bn euros.
  The move by Siemens and Mitsubishi comes just a day after rival bidder General Electric sweetened its offer.
  On Thursday, GE offered to create a joint venture with the firm's nuclear and energy businesses and to sell its profitable rail signalling business to Alstom.
  However, it did not increase its $17bn bid.
  Alstom, which also makes the high-speed TGV train, is seen as one of France's key industrial firms. The French government can therefore block a foreign takeover of the firm.
  As a result, all parties have discussed their offers with French President Francois Hollande, who is concerned about the break-up of Alstom and the loss of jobs.
  The rival bidders have also been sweetening other parts of their bid.
  GE's previous offer had been for a straight purchase of Alstom's power business. But it has now proposed to also create a joint venture with Alstom in the nuclear and energy business and to sell its rail signalling business to Alstom.
  "The alliance will retain and strengthen France's presence in the energy business and reinforce Alstom Transport," said GE's chief executive, Jeff Immelt.
  "It creates jobs, establishes headquarters decision-making in France and ensures that the Alstom name will endure."
  On Friday, Siemens also offered to enter into a "immediate" joint venture with Alstom in mobility management for the rail business, including signalling.
  "The specified proposal continues to preserve Alstom's current perimeter in almost all its activities, enhances its industrial sustainability, strengthens its financial structure," Siemens and Mitsubishi said in a joint statement.
summary: Siemens and Mitsubishi Heavy Industries have upped their offer to buy the energy business of France's Alstom, in the latest move by competing bidders.