NEW YORK, USA - New U.S. executive pay curbs likely will apply to only a handful of big banks getting federal bailout money. But the ripple effect may be felt well beyond Wall Street as Corporate America faces pressure to restrain CEO pay.

Pay experts doubt that the pay restrictions imposed on bailout companies by President Barack Obama on Wednesday would be voluntarily adopted by any company not already forced to accept them.

But they say the new rules are helping to change the tone of the CEO pay debate and putting many companies outside the financial sector further on the defensive to justify how they reward their leaders.

"People are focused now on executive pay and they don't trust it," said David Leach, an adviser to companies on executive pay issues. "It's going to go into other industries - this whole skepticism and lack of trust."

Leach, co-founder of Strategic Apex Group LLC, said U.S. companies will face mounting pressure as they prepare annual pay reports this year to explain things such as why a well-compensated executive could be entitled to receive severance pay when he is forced out, or why some top executives are free to use the company jet for personal flights at shareholders' expense.

Some of those payouts may make good sense as boards seek to retain and reward strong-performing leaders, he said, but companies will need to justify them.

Companies "will need to explain why this is right for their business," Leach said.

The new pay rules announced on Wednesday set a $500,000 annual cap on top executive salaries for companies getting taxpayer rescue funds. The restrictions are seen as widely popular with average Americans furious over executive excess and big Wall Street bonuses at a time of rising layoffs, devastating home foreclosures and stock market losses.

The rules could apply to companies outside of the financial industry, including auto manufacturers and other struggling big businesses that accept federal funds.

Additional pay for executives must be limited to restricted stock that cannot be cashed in until a company returns the government money with interest, according to the new rules.

Pay experts say that even before the new pay caps were laid down, corporate boards throughout many industries had been busy examining prior rules on companies accepting bailout funds that could be modified for their own use. These include requirements that companies ensure that executive pay plans are designed so as not to encourage CEOs to take inappropriate risks for the possibility of short-term gain.

Such language outlining companies' risk assessments is likely to be featured in many corporate pay reports this year, said Alan Levine, a partner at law firm Morrison Cohen LLP who focuses on executive pay matters.

Already, numerous companies in industries including manufacturing, technology and retail have responded to the new economic realities by announcing that their CEOs are accepting voluntary pay cuts. The reductions often have come as pay and benefits have been cut for rank-and-file workers.

"We have seen a big increase in companies voluntarily reducing their base salaries" for executives, said Alexander Cwirko-Godycki, research manager at executive compensation data tracker Equilar Inc. "From the middle of June until now, every single month you see more and more companies moving in that direction."

Among them are Motorola Inc , which said in December that Co-Chief Executives Greg Brown and Sanjay Jha would voluntarily take a 25 percent cut to their 2009 base salaries. The announcement came the same day the cell-phone maker suspended making matching contributions to its 401(k) retirement plan for employees.

Also in December, FedEx Corp said CEO Fred Smith would take a 20 percent pay cut, while pay for salaried personnel was being reduced by 5 percent and retirement plan contributions were suspended.

Wall Street chiefs have long been among the best paid in Corporate America. Pay experts say that with financial firms now being forced to rein in pay, companies elsewhere want to make sure that their chiefs do not appear to be overpaid.

"This can't help but impact other companies," Leach said. "They are seeing the whole groundswell. It's a populist issue."