WASHINGTON, March 6 (Reuters) - Nearly 50 Democrats in the U.S. Congress on Wednesday urged the Federal Trade Commission to probe oil and gas company deals and expand current investigations to protect consumers and industry competition.

The industry went on a $250 billion buying spree in 2023, taking advantage of companies' high stock prices to secure lower-cost reserves. Exxon Mobil Chevron Corp, and Occidental Petroleum made acquisitions worth a total of $135 billion in 2023.

The trend has continued this year with deals such as Chesapeake Energy agreeing in January to buy Southwestern Energy, a $7.4 billion deal that will make it the largest independent U.S. natural gas producer.

"If a small group of dominant firms is allowed to control this industry, American consumers and industry competition will only suffer," the Democrats, including Senate Majority Leader Chuck Schumer, and Representative Ro Khanna, wrote in a letter to the FTC.

"Therefore, we urge the FTC to extend its current investigations, open inquiries into these new deals, and take all appropriate actions to protect competition in this industry."

U.S. Energy Secretary Jennifer Granholm, asked about recent mergers at an event held by Axios, said she was concerned about monopolies because President Joe Biden is "obsessed about bringing down prices" including for gasoline.

But Granholm also expressed hope that mergers could accelerate a trend by some large oil and gas companies to act on climate and clean energy.

"Many of the majors, many of them not all ... have been taking action on climate and clean energy and a lot of the folks who are small level producers were not as interested, or didn't have the resources to address (those issues) so I'm encouraged that there seems to be a movement in this direction," Granholm said. (Reporting by Timothy Gardner; Editing by David Gregorio; Editing by David Gregorio)