The reward hike and guarantee of anonymity to whistleblowers is part of a major new campaign by the Competition and Markets Authority to crackdown on cartels.

The cartel watchdog hopes to uncover more illegal activity in industry’s like construction where bid-rigging was recently uncovered among 10 demolition contractors and 12 years ago found to be widespread with more than 100 firms fined nearly £130m for operating cover pricing rings.

Previously informants could be paid up to £100,000.

The reward is separate from the CMA’s leniency programme where a business or an individual that has participated in a cartel may escape sanctions if they come forward with information about the cartel, provided certain conditions are met.

Businesses found to have been involved in illegal cartels can be fined up to 10% of their annual turnover, individuals directly involved can face up to 5 years in prison, and company directors can be disqualified from holding director positions for up to 15 years.

Michael Grenfell, executive director of Enforcement at the CMA, said: “Cartels can cause serious damage to their customers, whether businesses or individual people, weakening price competitiveness.

“The CMA’s job is to stamp out illegal cartels, but because cartels are generally conducted in secret, we need to encourage people to come forward and provide us with the information we need to crack down on cartels and protect people and businesses from the harm they cause.

“For these reasons, we are today increasing the maximum financial reward for informants and whistleblowers who provide us with valuable information about cartels so that we can take action.”

Further cases of suspected cartel are currently under investigation.

To report cartel activity: email [email protected] or ring 0800 085 1664 or 020 3738 6888.

Rewards are at the discretion of the CMA. It will pay a reward if the information concerned is significant in nature and leads to enforcement action  against those involved in cartel activity.