UPDATE 1-United Airlines extends cancellations of Boeing 737 MAX flights through Aug. 3

(Adds United statement, company and industry details)

CHICAGO, May 24 (Reuters) - United Airlines said on Friday it is extending by one month its cancellations of Boeing Co 737 MAX flights, now through Aug. 3, leading to about 40 or 45 daily canceled flights.

It did not give a reason for the extension, but the August target date brings the airline more in line with rivals Southwest Airlines Co and American Airlines Group Inc , which have canceled 737 MAX flights through Aug. 5 and Aug. 19, respectively.

Boeing's top-selling 737 MAX aircraft has been grounded since March in the wake of two deadly crashes that killed a combined 346 people.

United, which trades under parent company United Continental Holdings Inc, operates 14 MAX jets and was due to take delivery of 16 more this year before the grounding.

"We'll continue to monitor the regulatory process and nimbly make the necessary adjustments to our operation and our schedule to benefit our customers who are traveling this summer," a United spokesman said in a statement on Friday. (Reporting by Tracy Rucinski in Chicago and Eric M. Johnson in Seattle Editing by Matthew Lewis)