European planemaker Airbus is in talks with Delta Air Lines to expand the U.S. carrier's existing order for A220 small jetliners, two people familiar with the matter said.

The deal for a top-up order of around a dozen aircraft could be signed at next week's Farnborough Airshow where the U.S. carrier is also widely expected to finalise an order for at least 100 Boeing 737 MAX airliners.

Airbus declined to comment on discussions with customers. Delta could not immediately be reached for comment.

The airline has ordered 95 Canadian-designed A220s of which it has taken delivery of 56, according to end-June Airbus data.

Reuters first reported in March that Boeing was in talks with Delta for some 100 of its 737 MAX 10 jets..

Delta Chief Executive Officer Ed Bastian said in June it was trying to reach a deal with Boeing. (Reporting by Tim Hepher, Editing by Louise Heavens)