UBS has contacted all of its charity clients to offer reassurance that their invested funds are safe, following the arrest of a rogue trader who is estimated to have cost the Swiss banking giant £1.3bn.

Head of charities Andrew Wauchope confirmed to civilsociety.co.uk this morning that the bank was getting in touch with all of its charity clients to assure them that no client positions are affected by the loss.

However, he refused to comment further and the press office would say no more than what was contained in its official statement released yesterday.  This read: “UBS has discovered a loss due to unauthorised trading by a trader in its Investment Bank.

“The matter is still being investigated, but UBS’s current estimate of the loss on the trades is in the range of USD 2 billion. It is possible that this could lead UBS to report a loss for the third quarter of 2011. No client positions were affected.”

UBS manages £1.05bn for 305 UK charities. Its largest charity client portfolio is in the range £50m-£100m while most portfolios (50 in total) fall into the £1m-£5m range.

In a letter to its 65,000 staff yesterday, the bank said: “We urge you to stay focused on your clients, who are counting on you to guide them through these uncertain times.”

Trader Kweku Adoboli, 31, who is understood to work in the European equities division, was detained in the early hours of Thursday and remains in custody.

BBC financial journalist Nigel Cassidy has warned that the reputation of UBS could be affected by the incident