CARTEL busters at the Office of Fair Trading are promising more raids on the roofing sector after it smashed its second large-scale price fixing ring in a year.
An investigation was originally sparked into corruption in the sector following information the OFT received from a single whistleblower.
An OFT spokeswoman said: 'A number of investigations in the roofing industry are still ongoing and will come to fruition in the next few months.'
The OFT has promised to spread its net wider from next month when the industry becomes an OFT priority area as part of an attempt to clean up construction, which the authorities believe is riddled with cartels.
The latest ring to be broken up involves 10 firms from north-east England and Scotland, which were fined a total of £830,000 last week.The OFT found the 10 had fixed prices or attempted to carve up a regional market.
But the overall fine was reduced to £560,000 because a number of firms were granted leniency for informing on rival cartel members.
In the north-east, Briggs Cladding & Roofing was let off its whole fine as the latest cartel's main whistleblower.
Mitrepoint, trading as Roofclad, had its fine cut in half to £12,554 after going to the OFT before an official investigation was launched.Hylton Roofing had its fine reduced by 35 per cent to £47,000.
Dufell Roofing and Hodgson & Allon were fined £74,000 while failed contractor Kelsey Roofing was hit with a £262,000 penalty. Another failed firm, Single Ply Roofing Systems, would also have been fined if it had generated a turnover in the previous business year.
In Scotland, contractor Pirie's penalty was reduced 55 per cent to £51,693 and for providing information unprompted about another market;
WG Walker and Company's 45 per cent was reduced to £16,415 and Lenaghen Roofing Services had its fine cut 35 per cent to £19,245.
The latest swoop follows the break-up of a roofing cartel involving nine companies in the West Midlands in spring 2004.
The OFT spokeswoman said: 'Roofing markets can be small and localised. Often ex-colleagues and friends are involved and are found to have shared market information to the detriment of the customer.'