SAN FRANCISCO -- San Francisco radio talk show host Bernie Ward has been indicted by a federal grand jury on charges of using the Internet to send and receive child pornography, his lawyer said.

The indictment is under seal, but the charges were confirmed by Ward's lawyer, Doron Weinberg, and by his employer, KGO radio.

Weinberg said Ward, 56, pleaded not guilty to the indictment before a federal magistrate in San Francisco Thursday.

He said Ward is due to reappear in court in late January before U.S. District Judge Vaughn Walker for a status conference and scheduling of a trial date.

Weinberg said the case stems from an "error of judgment" Ward made when he spent a few days in 2004 looking at pornography images and exchanging images with other adults when doing research for a book on hypocrisy.

The attorney said, "It's really tragic that the government has decided to prosecute him for a judgment he made as a journalist and to treat him as a child pornographer when he is not."

KGO Operations Director Jack Swanson said the station is for the time replacing Ward with a substitute on his two shows - a nighttime 10 p.m. to 1 a.m. show Monday through Friday and a Sunday morning show called Godtalk.

Swanson said, "Bernie Ward has been a valued, longtime employee of KGO Radio. We were just recently made aware of these serious charges and are surprised and concerned by their nature."

Swanson said, "As the matter is currently pending in federal court, we will have no additional comment at this time."

A spokesman for the U.S. attorney's office in San Francisco, which is prosecuting the case, could not be reached for comment.

Weinberg said the indictment was issued in late October but prosecutors agreed to keep it sealed while Ward conducted his annual Thanksgiving Charities drive, which according to KGO raises thousands of dollars annually for hungry and homeless people in the Bay Area.

Weinberg said he expects the indictment to be unsealed within the next few days, following Ward's court appearance today.

Weinberg said Ward wanted to learn about the culture of child pornography because he planned to include hypocrisy about pornography in his book. Ward never finished the book because the FBI searched his house and seized his hard drive in early 2005, the attorney said.

"It may have been an error of judgment, but he was not doing it to exploit children," Weinberg said.

Ward lives in San Francisco and is married and has four children.