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May 15 (Reuters) - China has agreed to buy 200 Boeing BA.N jets, with a potential for the order to rise to as much as 750 planes, U.S. President Donald Trump told reporters on Friday, adding that the planes would have GE Aerospace GE.N engines.

The deal "includes approximately 200 planes and a promise of up to 750 if they do a good job", Trump told reporters. More details on the deal such as which type of jets and when the order would be delivered were not immediately available.

The orders, if finalized, would mark Boeing's first major Chinese deal in nearly a decade, after the U.S. planemaker was largely shut out of the world's second-largest aviation market amid trade tensions between Beijing and Washington.

Shares of the U.S. planemaker had dropped nearly 4% on Thursday after Trump told Fox News Channel that China had agreed to buy 200 jets, a figure that was well below analysts' expectations. They were down about 1% in premarket trading on Friday.

Sources had earlier told Reuters that an order for roughly 500 jets was under discussion ahead of the meeting between Trump and Chinese leader Xi Jinping.

An order for more than 500 jets, if it materializes, would be the largest in aviation history, surpassing IndiGo's 500-aircraft deal for Airbus narrowbodies, though China's purchase would likely be split among its three major state-run carriers.

Boeing did not immediately respond to a Reuters request for comment.

Its CEO Kelly Ortberg and GE Aerospace GE.N CEO Larry Culp were among the group of American executives who accompanied Trump to China in hopes of clinching deals or resolving business disputes.

For China, such a big order would secure capacity to keep growing its aviation market as production of its home-grown COMAC C919 narrow-body falls short of ambitious targets.

It would also help Boeing narrow the gap with rival Airbus AIR.PA, which has pulled far ahead in China in recent years.

The deal would be a much-needed win for Trump, whose aggressive tariffs and other trade policies have so far failed to make much of a dent in the large U.S. trade deficit.