WASHINGTON — Attorney General Alberto Gonzales said Tuesday that Congress should require Internet providers to preserve customer records, asserting that prosecutors need them to fight child pornography.

Gonzales and FBI Director Robert Mueller have met with several Internet providers, including Time Warner Inc.’s AOL, Comcast Corp., Google Inc., Microsoft Corp. and Verizon Communications Inc.

The law enforcement officials have indicated to the companies they must retain customer records, possibly for two years. The companies have discussed strengthening their retention periods – which currently run the gamut from a few days to about a year – to help avoid legislation.

During those meetings, which took place earlier this summer, Justice Department officials asserted that customer records would help them investigate child pornography cases. But the FBI also said during the meetings that such records would help their terrorism investigations, said one person who attended the meetings but spoke on condition of anonymity because the meetings were intended to be private.

Testifying to a Senate panel, Gonzales acknowledged the concerns of some company executives who say legislation might be overly intrusive and encroach on customers’ privacy rights. But he said the growing threat of child pornography over the Internet was too great.

“This is a problem that requires federal legislation,” Gonzales told the Senate Banking Committee. “We need information. Information helps us makes cases.”

He called the government’s lack of access to customer data the biggest obstacle to deterring child porn.

“We have to find a way for Internet service providers to retain information for a period of time so we can go back with a legal process to get them,” he said.

At Tuesday’s hearing, Gonzales said he agreed with the sentiment of 49 state attorneys general who in a June letter to Congress expressed support for a federal law that would require longer retention of customer records.

“We respect civil liberties, but we have to harmonize this so we can get more information,” he said.

The subject has prompted some alarm among Internet service provider executives and civil liberties groups after the Justice Department took Google to court earlier this year to force it to turn over information on customer searches. Civil liberties groups also have sued Verizon and other telephone companies, alleging that they are working with the government to provide information without search warrants on subscriber calling records.

Justice Department officials have said that any proposal would not call for the content of communications to be preserved and would keep the information in the companies’ hands. The data could be obtained by the government through a subpoena or other lawful process.