By Marcus Leach

A 31-year-old man has been arrested by police in London in connection with unauthorised trading that has cost Swiss bank UBS in excess of $2 billion (£1.3 billion).

Kweku Adoboli, believed to work in the European equities division, was detained in the early hours of Thursday and remains in custody.

At present that figure is just an estimate, and with the bank still investigating the matter it could still rise.

An official statement from UBS has said that this could result in reported losses for the third straight quarter.

The bank, in their statement, went on to confirm that the unauthorised trading had not affected any customer accounts.

"The matter is still being investigated, but UBS's current estimate of the loss on the trades is in the range of $2 billion," the statement said.

"It is possible that this could lead UBS to report a loss for the third quarter of 2011. No client positions were affected."