After months of public feuding, there is no guarantee that an agreement can be reached, after previous attempts to avoid a high-profile trial in London this year were abandoned.

But two of the sources said the tone appeared more encouraging and negotiations had accelerated after an uneventful four-way meeting between the two sides and their respective regulators in Doha last week.

"There will be an agreement," one of the sources said, while another cautioned that the talks were still ongoing.

Airbus and Qatar Airways had no immediate comment.

(Reporting by Tim Hepher, Michel Rose, Andrew Mills; Editing by David Goodman)