NEW YORK (Reuters) - China's largest maker of auto parts won an auction for A123 Systems Inc (>> A123 Systems, Inc.), a bankrupt maker of batteries for electric cars that was funded partly with U.S. government money, A123 confirmed in a statement Sunday.

Wanxiang Group Corp's bid of $256.6 million topped a joint bid from Johnson Controls Inc (>> Johnson Controls, Inc.) of Milwaukee and Japan's NEC Corp (>> NEC Corp) for the maker of lithium-ion batteries.

The sale did not include A123's Michigan-based government business that works with the U.S. Defense Department, which was instead sold to Navitas Systems for $2.25 million, A123 said.

Wanxiang's winning bid came only one day after the Canadian government approved a controversial deal allowing China's state-owned oil company CNOOC (>> CNOOC Limited) to buy energy company Nexen Inc (>> Nexen Inc.) for $15.1 billion.

The sale must be approved by Delaware Bankruptcy Court judge Kevin Carey at a hearing scheduled for Tuesday.

Opposition to the deal will likely focus on the Committee on Foreign Investment in the United States, which would need to approve the sale to Wanxiang.

U.S. politicians and retired military leaders have already pressed the government panel to reject Wanxiang.

(Reporting By Edward McAllister; Editing by Diane Craft)