WASHINGTON (Reuters) - The U.S. Securities and Exchange Commission has ruled invalid an accounting practice used by some telecommunications companies to justify network capacity swaps, The Washington Post reported on Tuesday.

The Post said the new ruling means any companies that relied on the invalid procedure to artificially inflate revenues may be forced to restate their financial results, citing a memo circulated by the American Institute of Certified Public.

The AICPA, the accounting industry's trade and lobbying association, distributed the memo outlining the new policy at the request of the SEC, the report said.

The newspaper said the Aug. 6 memo made it clear that not all of the transactions at issue were in question. However, it warned a company's chief executive and chief financial officer "should be advised to give consideration to this matter prior to certifying the financial statements previously filed with the SEC."

The SEC, Congress and federal authorities are investigating bankrupt Global Crossing Ltd and Qwest Communications International Inc . -- looking into whether the telecommunications firms engaged in network capacity swaps -- where they bought and sold an equal amount of capacity from network carriers at the same time -- as a way of artificially inflating revenue.

Global Crossing and Qwest missed the SEC's deadline on Thursday for submitting affidavits from their chief executives and chief financial officers certifying financial results.

Both companies said they were still reviewing their books and accounting policies. The Post said they declined to comment on the SEC's new guidance regarding swaps.