Bob Diamond, John Varley and other senior members of Barclays’ former management are to be questioned under caution by the UK’s Serious Fraud Office, in an acceleration of its probe into alleged corrupt arrangements in Qatar as part of the bank’s emergency cash call in 2008.

For Barclays, which last week launched a restructuring plan to boost struggling profitability, the news is an unwelcome reminder of the legacy issues that still hang over it. “They’ve just sliced off two arms and a leg, and still someone’s out to get them,” said one person involved.

A dozen individuals have now been either interviewed under caution or called for interview by the SFO, according to people familiar with the probe. Aside from Mr Diamond and Mr Varley, both former Barclays chiefs, they include Roger Jenkins, former head of the bank’s tax advisory business, and Chris Lucas, former finance director.