The Securities and Exchange Commission has sent letters to almost 300 U.S. companies asking for further details into their executive compensation practices, the Wall Street Journal reported on Friday.

The action comes amid growing public concern over options backdating scandals and the levels of executive pay, and a year after the S.E.C. tightened regulations requiring companies to provide more information about stock-option awards and to report the total compensation of top managers.

Recipients of the letters, sent last week, include Pfizer, Schering-Plough, Bristol-Meyers Squibb, Prudential Financial, Coca-Cola, andGeneral Electric, according to the Journal.

The commission's new rules are intended to increase transparency for shareholders, letting them compare pay practices across publicly traded companies.

But many of the companies involved are hesitant to release details on performance targets, claiming that much of the information is sensitive and confidential.

The S.E.C. will require most recipients of the letters until Sept. 21 to respond to the inquiry and plans to make the letters public later this year, the Journal reported.