Top directors at Barclays including chairman Marcus Agius and president Bob Diamond have shelled out more than £6m (€8.9m) buying shares in the UK banking group, only days before it kicks off a £2.4bn share buyback.

Existing Barclays directors bought £3.8m worth of shares on the open market yesterday, while chief operating officer Paul Idzik spent $2m on Barclays' American depositary shares, according to a stock market announcement by the bank today.