The Office of Fair Trading (OFT) said the merger created a "near-monopoly" in the supply of kaolin.

BBC: China clay pit

China clay - also known as kaolin - is used in the manufacture of sanitary ware, paper and paints.

BBC: China clay pit

In order to make the white tableware, Wedgwood imported kaolin clay from the Cherokee tribe in the American colonies.

ECONOMIST: Feat of clay

It also reduced the number of companies supplying kaolin for specialty applications in the UK from three to two, an OFT statement added.

BBC: China clay pit

As both Imerys and Goonvean had been active in the extraction, processing and supply of kaolin products from deposits and facilities in Cornwall before the merger, the OFT concluded there was a realistic prospect the merger could result in a "substantial lessening of competition".

BBC: China clay pit