The Government has handed data regulator, the Information Commissioner’s Office, the power to punish “serious incidents” by fining offenders.
The move is part of the UK’s response to an EU law on privacy.
In addition to tighter controls over email and telemarketing, companies will also be required to give consumers the chance to insist that companies do not take data from their computers for use in behavioural targeting.
Companies that do not provide an “opt-out” option on each display ad that uses the ad could also be hit a fine of up to half a million pounds.
The ICO’s new powers and the law change come into force 25 May.