In a victory for Boeing , a preliminary World Trade Organization panel is likely to rule on Friday that European governments illegally subsidized Airbus aircraft, the Wall Street Journal said, citing trade officials, lawyers and executives from both sides.

The expected ruling in the biggest trade dispute in the WTO's nearly 15-year history has been years in the making.

Britain three weeks ago pledged 340 million pounds ($553.5 million) in loans to help Airbus develop the A350 widebody passenger jet, which is intended to compete with Boeing's much-delayed 787 Dreamliner.

Germany would provide 1.1 billion euros ($1.57 billion) and France 1.4 billion euros ($2.0 billion), German and French officials have said.

Last week, a Ted Austell, Boeing's vice president for government operations, told reporters that he hoped the expected ruling would force European governments to reconsider plans to help finance the A350.

Boeing and Airbus could not be immediately reached for comment by Reuters.

($1=.6143 Pound =.7006 Euro)

(Reporting by Ajay Kamalakaran in Bangalore; Editing by Muralikumar Anantharaman)