A former junior UBS trader who was trained by Kweku Adoboli described his ex-colleague as "unfriendly, unpleasant, distant and superior", and denied having full knowledge of his activities.

Christophe Bertrand, a junior trader who worked with Adoboli on UBS's London-based ETF trading desk before the Swiss bank reported it had suffered a $2.3bn unauthorised trading loss in September 2011, made the comments yesterday at Southwark Crown Court during a criminal case against Adoboli.