The Daily Telegraph reports that the bank's board called a late meeting Wednesday to review the terms of his contract and decide the bank's legal position in regard to Diamond's £18m of unvested share options and £4m-plus of benefits.
He is also due more than £2m in lieu of a year's salary and pension after being ejected from the bank on the direction of the Bank of England Governor over the Libor scandal.
A source close to the board told the newspaper: 'Barclays needs to establish where it stands legally with regards to Bob's contract and entitlements. The bank is fully aware of the high emotions around this and the need for there not to be any false moves'.
The newspaper also says that Andrew Bailey, the head of the Financial Services Authority's bank supervision arm, was the senior regulator who warned Barclays' executives of failings in its culture, the Times reports.
Bailey, the highest ranking bank supervisor in the City, told a board meeting in February of his misgivings about the bank's behaviour, it reported, citing sources.