* Order 20 Boeing 787-9 and 20 Airbus A350-900 planes
* Order has list volume price of $12 billion
* To be delivered between late 2022-2027
* To sell six Airbus A380 back to Airbus in 2022/2023 (Adds details, quote)
BERLIN, March 13 (Reuters) - Lufthansa has ordered 20 Boeing 787-9 and 20 additional Airbus A350-900 long-haul planes to replace its older four-engine aircraft as it seeks to boost the fuel efficiency of its fleet, the airlines group said on Wednesday.
The German company said it has also agreed to sell six of its 14 Airbus A380 planes back to Airbus in 2022/2023 for economic reasons.
Airbus said last month it would scrap production of the A380 superjumbo from 2021 following lacklustre sales. The decision reflected a dearth of orders as airline bosses shied away from bulky, larger planes that are harder to fill.
Qatar airways said last week it would phase out its A380 planes from 2024.
Lufthansa said the new aircraft will be delivered between late 2022 and 2027. It did not disclose how much it had paid for the planes which have a list-price investment volume of $12 billion, but said it had negotiated a significant price cut.
"In addition to the cost-effectiveness of the A350 and B787, the significantly lower CO2 emissions of this new generation of long-haul aircraft was also a decisive factor in our investment decision," Chief Executive Carsten Spohr said in a statement.
Lufthansa currently operates a long-haul fleet of 199 aircraft. It said the new, more economical aircraft will lower its operating cost compared to earlier models by around 20 percent.
The airline will also seek to reduce the complexity of its fleet over the next few years by taking seven aircraft types out of service to help reduce maintenance costs and the supply of replacement parts. (Reporting by Caroline Copley; editing by Thomas Seythal and Michelle Martin)