(Reuters) — China is considering resuming purchases of Boeing's (BA) 737 Max aircraft when the U.S. and Chinese presidents meet this week at the APEC summit, Bloomberg News reported on Sunday, citing people familiar with the matter.

Chinese President Xi Jinping is not expected to unveil a formal order for the 737 Max; aircraft commitments that are not a firm sale often take the form of a memorandum of understanding or letter of intent, the report said, adding that the terms of any potential agreement were under discussion and could change or fall apart before the heads of state meet on Wednesday.

Boeing is still waiting to resume deliveries of its bestselling 737 MAX to Chinese airlines more than four years after they were halted following two deadly crashes. The company had said that as of the end of June, about 90% of its 737 Max jets in China had resumed commercial operations.

The company has been all but shut out of new orders from Chinese carriers since 2017 amid rising political and trade tensions between Beijing and Washington.

Boeing in September slightly increased its annual 20-year forecast for new plane deliveries to China, citing economic growth and increasing demand for domestic travel.

The U.S. planemaker said that China's fleet would more than double to nearly 9,600 jets over the next 20 years and that its domestic aviation market would be the largest in the world by the end of the forecast period, with demand for 6,470 single-aisle planes such as the Boeing 737 MAX family.

Reuters reported in April that China's aviation regulator published a report that Boeing viewed as a key step for the U.S. planemaker to resume deliveries, but none have resumed.

Boeing declined to comment on the Bloomberg report.

(Reporting by Gokul Pisharody in Bengaluru; Editing by Tom Hogue and Gerry Doyle)