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 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), according to the letter sent Tuesday afternoon. Siemens also says in the letter it is "disappointed by the lack of cooperation" from Alstom chief Patrick Kron. Both Siemens and US giant General Electric are competing for Alstom's energy business and the French government is keeping a close eye on any deal given the strategic importance of the business and the need to safeguard jobs. A source said late Tuesday that Alstom's board has approved the US group's bid of 12.35 billion euros.