A UBS spokeswoman said: 'We can confirm that four people left, and that the departures related to breaches of internal procedures. No losses were incurred by the bank or its clients.' UBS refused to name those who had left or to give reasons for their departure.
But market sources said the others included Dave Tresadern, head of the forward desk, who resigned. Barry Johnson, a director on forex forwards, also left.
The fourth departure is thought to have been an accountant in a back office.
The sources said the affair had nothing to do with client accounts, but that the problems were to do with internal banking procedures that had not been followed.
There is no suggestion that money has been lost or that anything more serious than internal procedures was involved.
The two senior departures are thought to have been because Mr May and Mr Tresadern took line responsibility for procedural problems that occurred in Mr Johnson's area.
UBS is bound by market regulations to report transgressions of its internal rules to the regulatory authority, which in the case of foreign exchange is the Bank of England. But there was no indication last night of whether action was likely by the regulators.
UBS is now faced with the problem of recruiting a new foreign exchange team, which has been denuded by the sudden senior departures.
UBS is still fighting the case of Terry Smith, the analyst who left last year after problems over his book on the way companies use creative accounting techniques to mislead investors.Reuse content