WASHINGTON — Three months after the government seized control of Fannie Mae and Freddie Mac, lawmakers yesterday blamed former top executives at the mortgage giants for fueling the financial market turmoil that has dragged the country into a recession.

Internal e-mails and other documents released by the House Oversight and Government Reform Committee show that former Fannie Mae CEO Daniel Mudd and former Freddie Mac CEO Richard Syron disregarded recommendations that they avoid riskier types of loans.

"Their irresponsible decisions are now costing the taxpayers billions of dollars," said Rep. Henry Waxman, D-Calif., chairman of the committee, which reviewed nearly 400,000 internal documents from Fannie and Freddie.

Republicans argued that the primary causes of the financial meltdown were weak regulation of Fannie and Freddie and Clinton administration policies to promote homeownership. "We knew a long time ago that this train was going to crash," said Rep. Christopher Shays, R-Conn.

Democrats acknowledged the two government-sponsored companies contributed to the financial crisis. But they stressed that Wall Street banks — not Fannie and Freddie — led the decline in lending standards that caused mortgages to start defaulting in huge numbers two years ago.

Two months after federal regulators seized the two companies in September, Freddie Mac asked for an injection of $13.8 billion in government aid after posting a huge quarterly loss. Fannie Mae has yet to request any government aid but has warned it may need to do so soon.

Fannie and Freddie own or guarantee around half the $11.5 trillion in U.S. outstanding home loan debt. The two companies are the engines behind a complex process of buying, bundling and selling mortgages as investments.

They traditionally backed the safest loans — 30-year fixed-rate mortgages that required a down payment of at least 20 percent. But in recent years, they lowered their standards, matching a decline fueled by Wall Street banks that backed the now-defunct subprime lending industry.

Rep. Carolyn Maloney, D-N.Y., grilled Syron about Freddie Mac's decision to fire David Andrukonis, its former chief risk officer. Andrukonis had warned as far back as 2004 about the risks posed by loans in which borrowers didn't provide proof of their incomes or detail their assets, according to e-mails released by the committee.

"Do you regret firing him?" Maloney said. "Do you regret buying these risky loans? Do you regret the way you led — and I would say mismanaged — this company?"

Syron said Andrukonis "was fired for a variety of reasons. It was not primarily for his having a view on credit."

Lawmakers also pressed Mudd about an internal Fannie Mae presentation from June 2005. It showed the company at a key juncture. Its competitors on Wall Street were starting to reap lucrative fees on investments backed by risky loans. Fannie Mae had to decide whether to compete in that market or take the less risky, but also less profitable, path.

Fannie Mae executives worried at the time about "becoming a niche player" and "becoming less of a market leader" at the time, according to the confidential internal presentation, which noted that mortgage securities sold by Wall Street investors exceeded those sold by Fannie Mae for the first time in 2004.

Lawmakers were frustrated by what they called a lack of willingness among Syron and Mudd, plus former Fannie Mae CEO Franklin Raines and former Freddie Mac CEO Leland Brendsel, to share any of the blame for the companies' fortunes.

"All four of you seem to be in complete denial that Freddie and Fannie are in any way responsible for this," said Rep. Darrell Issa, R-Calif. "Your whole excuse for going to risky and unreasonable loans that are defaulting at an incredibly high rate is that everyone is doing it."

Repeated attempts to impose tighter regulation on the two companies were thwarted by the their powerful lobbyists. The companies, which are now banned from lobbying, spent $177 million on lobbying over the past 20 years, according to the Center for Responsive Politics.

Raines defended his company's lobbying, saying "Fannie Mae, like any other corporation owned by shareholders, came to Congress and expressed its views."