PHOENIX, Dec 27 (Reuters) - Regional airline Mesa Air Group, Inc. (MESA) said on Thursday that it had taken delivery of two new Embraer (EMBR3) jets and finished financing for two more aircraft for delivery early next year. Mesa Air said the four Embraer ERJ 145 aircraft will be used as part of US Airways Group's (U) Express system and will bring Mesa's total ERJ fleet to 25 planes. The airline said that it expects to take delivery of 13 regional jets over the next two years. Regional jets, which carry 30 to 70 passengers, are seen as a more efficient and popular replacement for turbo-prop aircraft on short- and medium haul routes. Mesa Air Group shares finished Thursday trading up 8 cents, or 1.14 percent, at $7.08 on the Nasdaq.