A U.S. television network continues to stand by its recent report questioning President Bush's military service during the Vietnam era, despite questions about the authenticity of documents on which the story was based.

CBS News said Wednesday it is unmoved by reservations expressed since the broadcast by experts it hired to authenticate memos used in the story. One expert said she told CBS of her concerns before the story aired.

Last week, CBS-TV's 60 Minutes said the memos suggested Mr. Bush entered the National Guard with the help of family connections, then failed to fulfill his obligations. The memos were allegedly written by one of Mr. Bush's commanding officers, Jerry Killian, who has since died.

Several experts have said the 30-year-old memos appear to have been written with a modern-day word processor.

The White House says Mr. Bush completed his service requirements.