WASHINGTON, May 30 (Reuters) - U.S. Senate Majority

Leader Chuck Schumer and 22 other Democratic Senators on

Thursday asked the Attorney General to investigate allegations

of collusion and price fixing between the oil industry and the

Organization of the Petroleum Exporting Countries (OPEC).

Earlier in May, the Federal Trade Commission gave the

go-ahead to Exxon Mobil's ( XOM ) $60 billion purchase of

Pioneer Natural Resources, but barred former Pioneer CEO Scott

Sheffield from Exxon's board on allegations he attempted to

collude with OPEC to raise oil prices.

"These reports are alarming and lend credence to the fear

that corporate avarice is keeping prices artificially high," the

senators said in a letter to Attorney General Merrick Garland

and his antitrust chief Jonathan Kanter.

"We therefore urge the Department of Justice to investigate

the oil industry, to hold accountable any liable actors, and to

end any illegal activities," the letter said.

Sheffield coordinated efforts with U.S. shale oil producers

to constrain their output and raise energy prices, the Federal

Trade Commission said on May 2.

Widely considered the dean of U.S. shale because of his long

tenure and blunt comments on industry output and spending,

Sheffield used his influence "to align oil production across the

Permian Basin in West Texas and New Mexico with OPEC+," the FTC

added at the time.

Sheffield's lawyers did not immediately respond to a request

for comment.

Earlier this week, he asked the FTC to dismiss the ban. "At

no time did government officials and Mr. Sheffield exchange

competitively sensitive information," said Sheffield's counsel

Cleary Gottlieb Steen & Hamilton.