UPDATE 1-Boeing says Qantas buys more 737s worth $2.3 bln

(Adds dateline, details on year-to-date orders)

NEW YORK, Dec 20 (Reuters) - Boeing Co (BA.N) said on Thursday that Australian airline Qantas Airways Ltd (QAN.AX) ordered 31 next-generation 737-800 single-aisle planes, worth about $2.3 billion at list prices.

The deal is Qantas' second large single-aisle order this decade. It bought 38 737s in 2001, which have now mostly been delivered.

The new order brings the number of 737s sold this year to 713, making it by far Boeing's most popular plane with airlines.

Boeing now has 1,213 net orders for the year so far, already its highest tally ever, well ahead of its record of 1,044 last year.

The Chicago-based company is neck and neck with European rival Airbus (EAD.PA) in the race for orders this year. The final tally for both companies, adjusted for cancellations, should be made public early in January. (Reporting by Avishek Mishra in Bangalore, Bill Rigby in New York; Editing by Deepak Kannan, Richard Chang)