Ali Nikpay, OFT Senior Director, said: “While we concluded that the merger raised no competition issues on a national basis, we were concerned that builders in some local areas could lose out as a result of reduced competition.

“We are therefore considering branch sales offered by the parties to resolve these issues.”

The OFT concluded that the merger would not give rise to competition concerns nationally because sufficient competitors would remain in the market.

It also said that the presence of Saint-Gobain companies upstream of Jewson, in the plasters and plasterboard sectors would not give rise to competition concerns.

But after a survey of nearly 10,000 builders, the OFT concluded that the deal raised substantial competition concerns in 22 local areas in England, Wales and Scotland.

This was because there were few remaining general builders merchants in these local areas and the OFT was concerned that builders and other tradesmen might see an increase in prices for building materials as a result.

To address these concerns, Jewson has offered to sell at least one branch in each of the 22 affected local areas to restore pre-merger competition levels.

Jewson and Build Center are two of the country’s largest general builder’s merchants.

Jewson has a chain of 510 general builder’s merchants in the UK operating under the Jewson and ‘Gibbs and Dandy’ brands and also operates some specialist building materials distribution businesses.

Build Center has 149  branches in the UK, including a number of specialist glass, ironmongery and timber outlets.