BZ Gruppe, the Swiss investment company, has yet to hire a financial adviser for the sale of its Sfr834m (€570m) stake in Lonza Group, despite a statement from the chemical company that the deal would be completed in the next few weeks.

Lonza said in a statement that BZ, which is run by high-profile investor Martin Ebner, is to sell its 20% holding. But Kurt Schiltknecht, a spokesman for BZ, said the firm was not using an investment bank for the process: "We don't need any outside advice for the moment."