The proposed merger between UK media congloms Carlton Communications and United News & Media has hit a setback after being referred to the Competition Commission.

The widely-expected decision by trade and industry secretary Stephen Byers comes after the Office of Fair Trading (OFT) raised concerns regarding both TV programming and advertising. The Commission is to deliver its findings in May.

The would-be partners had hoped to avoid a referral, but Granada Media Group, a rival ITV commercial broadcaster, appears to have put pressure on OFT after expressing an interest in buying Carlton or United. Granada is now expected to come under the Commissions' spotlight along with Carlton and United.