British companies must end "pockets of resistance" to the growing crackdown on price-fixing, the competition watchdog has warned as it pledged to bring more prosecutions following this month's landmark jailing of three executives.

Simon Williams, the Office of Fair Trading's head of cartels, has unveiled a twin-track approach to targeting abuses, with criminal charges for "hard-core" manipulation and tougher use of director disqualification in less serious cases.