In an appeal for boardroom honesty, he pledged that his Justice Department would hold accountable any firms engaging in corruption and deceit.

We expect high standards in our schools, we expect high standards in corporate America as well, and I intend to enforce the law to make sure that there are high standards

President Bush

"Corporate America has got to understand there is a higher calling than trying to fudge the numbers, trying to slip a billion here and a billion here and... hope nobody notices," he said.

Mr Bush, who was speaking at a Republican Party fund-raiser, did not mention by name the WorldCom case which rocked the international business world this week.

WorldCom, the US telecommunications giant, revealed $3.8bn in accounting irregularities and office equipment giant Xerox disclosed an accounting black hole of nearly $2bn.

The BBC's Justin Webb in Washington says that it was President Bush's strongest attack yet on America's corporate bosses.

Aware his administration is seen as a friend of big business, he is working hard to try to distance himself from what is happening in American boardrooms.

Fundamentals 'very strong'

Friday is the third day in a row that Mr Bush has promised to crack down on business mismanagement.

The scandals that shook Wall Street

Enron's accounts turned out to be an elaborate scam Andersen approved the WorldCom and Enron accounts Other firms under fire: Xerox, Adelphia, Tyco, Global Crossing Click here for more details

"I'm not concerned about the fundamentals of our economy. I think they are very strong," Mr Bush said.

"People are concerned, however, about whether or not the balance sheets of corporate America are open, whether or not the numbers are real."

Mr Bush will devote his Saturday radio address to the subject of corporate responsibility and will visit New York on 9 July to urge US businesses to adopt better management practices.

Our correspondent says Mr Bush is likely to back moves to tighten up on accountancy practices in the US, including the establishment of a new regulatory authority to oversee the scandal-tainted sector.

On Wednesday Mr Bush condemned the WorldCom fraud as "outrageous".

WorldCom said its chief financial officer Scott Sullivan improperly booked expenses as investment in order to make the company look much healthier than it actually was.

Bankruptcy now looks like a serious possibility for the telecoms firm as its refinancing talks are likely to be thrown into disarray.