Sex offenders' e-mail addresses are to be passed to social networking sites like Facebook and Bebo to prevent them contacting children.
The home secretary told BBC News: "I have been very encouraged by the willingness of industry to actually work with us.
"They want children and young people to be safe when they're using their sites.
Further concerns surround working with websites based abroad over which the UK has no jurisdiction.
Both Facebook and My Space are based in California.
Home Secretary Jacqui Smith said she wanted children to be "free from fear".