Siemens has improved its bid to Alstom for the French company's energy business, according to a letter from the German engineering giant to Alstom and seen by AFP Wednesday. Siemens has offered to hand Alstom its underground as well as its high-speed train business in return for its energy activities, which it values at between 10.5 and 11 billion euros ($14.5-15.2). Siemens also says in the letter it is "disappointed by the lack of cooperation" from Alstom chief Patrick Kron.