Britain has urged the US to co-operate in the fight against unsolicited e-mail, or spam, playing down transatlantic differences in legal approaches to the problem.
Spam is said to make up half of all e-mails sent
A UK internet envoy visiting Washington said collaboration was improving.
Britain has recently announced a ban on spam - a move the US Congress is not considering.
The BBC's David Bamford in Washington says the US position is vital, because most spam originates from there.
Following the money
UK internet adviser Andrew Pinder met Republican and Democratic senators in Washington on Tuesday, urging them to tighten up anti-spam legislation being considered in Congress.
Afterwards he said co-operation between the two countries was improving, notably with respect to child pornography.
"The prosecutions both in the US and the UK illustrate that," he said.
US investigators are trying to use improved technology to trace the transmission route of internet pornographers.
But with spammers easily able to hide their point of origin, one strategy is to "follow the money", by tracking credit card payments made in response to offers by spammers advertising fraudulent or pornographic services.
The Supreme Court meanwhile announced on Tuesday that it intended to make a ruling on the Bush administration's controversial Child Online Protection Act.
The government says the legislation will help prevent unsolicited pornography reaching children. But lower courts have struck it down on freedom of speech grounds.
Under new European Union legislation endorsed by the UK, companies will have to get permission from an individual before they can send them an e-mail or text message.
Some anti-spam advocates say the move does not go far enough, because it does not protect business e-mail addresses.
Unsolicited e-mail, or "spam", cost European businesses an estimated 2.25bn euros ($2.6bn) in lost productivity last year, according to the European Commission.
The leading proposals being considered by the US Congress would allow businesses to e-mail consumers until asked to stop.