WASHINGTON — The spread of child pornography, fueled by technology and the Internet, is outpacing efforts to combat it, the Justice Department said Monday in a report to Congress that promises more arrests, prosecutions and better coordination among federal, state and local authorities.

Attorney General Eric Holder said the distribution of child pornography, the number of images being shared online and violence against child victims all have increased.

“Tragically, the only place we’ve seen a decrease is in the age of victims,” Holder said in a speech at the National Center for Missing and Exploited Children in Alexandria, Va.

The report, ordered by Congress in legislation approved two years ago, concedes that the market for child pornography continues to grow rapidly and determining its size is impossible.

“The number of offenders accessing the images and videos and the quantity of images and videos being traded is unknown,” the report said.

Creating or possessing images that depict the sexual abuse of children is illegal. There is no First Amendment protection for child pornography.

In announcing a national strategy for preventing child exploitation, Holder laid out several steps that he said would help authorities make progress:

_ The U.S. Marshals Service will target the “top 500 most dangerous” sex offenders who have not registered with authorities in the states where they live.

_ The Justice Department is creating a database intended to increase cooperation among authorities at all levels of government that investigate child porn cases.

_ Thirty-eight new prosecutors will be hired for child porn cases.

The increased attention to fighting child pornography already has led to record numbers of prosecutions and tips. More than 8,600 people have been prosecuted at the federal level since October 2006. State and local authorities focused on the use of the Internet in child sexual exploitation reported that documented complaints of online enticement of children more than tripled from 2004 to 2008 and complaints of child prostitution rose more than 10 times.