Mexico's government said the oversight arm of Congress has found no diversion of funds or embezzlement at state-owned oil company Petroleos Mexicanos, which had faced allegations of hiding losses through accounting trickery.

The Public Function Secretariat, or SFP, said in a statement that Pemex "duly and promptly" responded to the doubts Congress' ASF agency had raised over the apparent disappearance from Pemex's books of a $30 billion loss in 2009 by its exploration and production arm, or PEP.

"In accordance with procedures established in the Law on Control and Accountability of the Federation, the ASF reported in recent days that the observation was addressed in a satisfactory manner and shown to be an issue related to the consolidation of financial accounts," the SFP said.

It added that the ASF was satisfied with the information provided by Pemex and concluded that the recording of the PEP unit's results on the parent company's books "did not affect the financial accounts of the Pemex group as a whole."

On May 8, leftist opposition lawmaker Esthela Damian proposed a congressional resolution to demand that Pemex CEO Juan Jose Suarez Coppel appear before the legislative body and explain the alleged accounting discrepancy detected by the ASF.

According to Damian's resolution, in a Feb. 15 report on federal government accounts, the ASF reported that a 2009 loss of 398.57 billion pesos (just under $30 billion) by the PEP subsidiary had been eliminated and recorded as an increase in the assets of Pemex's corporate division, Pemex Corporativo.

It said Pemex gave no technical basis for recording the loss as assets and the company's board of directors did not authorize the move.

Pemex, for its part, had responded in a statement that the essence of the observation made by the ASF referred to an accounting procedure the company has followed since 1993.

The company said that as part of that accounting method, the profits or losses of Pemex subsidiaries are transferred to Pemex Corporativo for consolidation purposes.

Pemex said that in following that method, the sum in question was recorded in Pemex Corporativo's books as accounts receivable - under the category of "increase in investments in subsidiaries." EFE