A bill introduced to the US House of Representatives would require ISPs to record all users' surfing activity, IM conversations and email traffic indefinitely.

The bill, dubbed the Safety Act by sponsor Lamar Smith, a republican congressman from Texas, would impose fines and a prison term of one year on ISPs which failed to keep full records.

"A crime is still a crime, whether it occurs on the street or on the internet," said Congressman Smith.

"In this age of increasing digital and technological sophistication, cyber-crimes and cyber-terrorism pose a serious threat to the US. Law enforcement and the private sector must be prepared to deal with these crimes."

The bill includes a separate clause that would force the owners of sexually explicit websites to include warning labels on their web pages, or face jail.

Also included is a 20-year "jail tariff" for anyone ordering child pornography that crosses state borders, with a $150,000 fine for the ISP that allowed the transaction to take place.