Washin<\h>gton (Bloomberg) — A US House of Representatives panel is investigating firms that advise companies on executive compensation while providing other services to determine whether conflicts of interest contribute to excessive pay packages.Representative Henry Waxman, who chairs the House Committee on Oversight and Government Reform, sent letters to six firms this week asking them to describe executive-pay and other services and the fees they collected from 2002 to 2006.

"Almost everyone agrees the extravagant increases in executive compensation make no sense," Waxman, a California Democrat, said in a statement.

"The question I'm looking at is whether potential conflicts of interest" between consultants and clients "might play a role" in some of the decisions.

Executive compensation has drawn closer scrutiny in Congress as Democratic leaders who took control January look to spotlight economic inequalities, including the growing income gap between corporate executives and working families.

Representative Barney Frank, the Massachusetts Democrat who chairs the House Financial Services Committee, has made the issue a priority, introducing legislation in March that would give shareholders more say on executive pay packages.

"Shareholders and investors have expressed concerns that a compensation consultant's ongoing business relationships with a company could compromise the independence of the advice the consultants provide to the company's board about executive compensation," Waxman wrote in the May 8 letters.

Some firms that advise on pay also offer consulting on employee-benefit and pension plans, Waxman wrote.

Little is known about the extent of this practice since the US Securities and Exchange Commission doesn't require pay consultants to disclose other services, the letter said.

Waxman asked the consultants to get back to his committee by May 29 with a list of the companies among the 250 largest US firms that they provided with executive-pay and other services.

For each company, he asked them to detail the services offered and the revenue collected for each service.

The letters were sent to the leaders of New York-based Pearl Meyer & Partners, Stamford, Connecticut-based Towers Perrin, New York-based Frederic W. Cook & Co., New York-based Mercer Human Resource Consulting, Lincolnshire, Illinois-based Hewitt Associates, and Arlington, Virginia-based Watson Wyatt.