The government is to implement laws that prevent companies advertising falsely on the internet from next month.

The anonymity that the web provides has allowed some firms to set up sites that pose as consumer reviews ­ but are actually little more than free advertising. Others post favourable comments on legitimate review sites.

But under new rules to be implemented in April, this practice will be banned, according to Philip Carnell at law firm CMS Cameron McKenna.

“Companies, or those that do their advertising, will no longer be able to falsely pose as consumers to write favourable reviews ­ it will become a criminal offence,” he said.

The law - ­ originally the EU’s Unfair Commercial Practices Directive - ­ was due to be brought in last year, but suffered delays.

Penalties are unlikely to be too severe at first, especially as the Office of Fair Trading (OFT) and Trading Standards ­ the bodies that police the act ­ have limited resources.

The OFT is likely to use the media to “name and shame” companies that break the laws rather than pursuing expensive prosecutions.

Policing the web is difficult, and offences will probably not have a dedicated unit aimed at prosecuting them, said Carnell.

“There are internet forums dedicated to unveiling big businesses that do this kind of thing ­ most of the prosecutions will come from companies being reported to the regulators,” he said.