WASHINGTON — U.S. President George Bush has signed a bill he said will help protect children from the “unforgivable cruelty” of exploitation of danger.

Bush signed the Adam Walsh Child Protection and Safety Act of 2006 Thursday in the presence of several families whose children suffered violence. The act is named for a 6-year-old Florida boy kidnapped and killed in 1981.

“Protecting children is our solemn responsibility,” Bush said. “It’s what we must do. When a child’s life or innocence is taken it is a terrible loss. It’s an act of unforgivable cruelty.”

The White House said the law expands the National Sex Offender Registry, toughens federal penalties for crimes against children, makes it harder for predators to reach children through the Internet and creates a National Child Abuse Registry.

“By enacting this law we’re sending a clear message across the country: Those who prey on our children will be caught, prosecuted and punished to the fullest extent of the law,” the president said.