PetroChina Company Limited (PetroChina), China's largest oil and gas producer, announced on Monday that it will ally with Shell through a joint venture to acquire Arrow Energy Limited, an Australian energy company, for 3.5 billion Australian dollars (3.15 billion U.S. dollars).

Shell and PetroChina will pay AU$4.70 a share for Arrow's Australian business. The bid is 5.6 percent more than A$4.45 offer made on March 8. Arrow's international assets will be housed in a new company called Dart Energy Ltd, which may be worth as much as A$400 million, according to analysts. Arrow stock holders will get one share in Dart for every Arrow share they own.

Arrow shares slipped as much as 21 cents, or 4 percent, to A$5.08 in Sydney and were trading at $5.11 at 11:26 am local time, having climbed 52 percent to a record A$5.29 since the takeover offer as investors bet PetroChina and Shell would sweeten their initial A$3.26 billion bid.

PetroChina's parent, China National Petroleum Corp, got a discounted $30 billion loan last year to fund overseas expansion. The Arrow deal gives Shell reserves to feed its Curtis Island liquefied natural gas project, one of more than a dozen planned LNG ventures in Australia aimed at tapping rising Asian demand.

"Australia is becoming more of a regional focus" for Shell, Nik Burns, a Melbourne-based analyst for RBS Morgans, said by phone March 19. "It's going to be one of their key growth areas, and the company as a whole is looking to move more upstream and move away from their downstream side."