UBS will today mount an extraordinary legal challenge to prevent departing executives from poaching valuable clients.

The embattled Swiss bank is seeking a temporary High Court injunction against Vestra Wealth, a new wealth manager, as well as its founder, David Scott, and four senior fund managers.

The fund managers – Duncan Carmichael-Jack, the A-rated stock-picker who ran UBS’s Elite Income fund, David Guild, Neil Pedley and Paul Pollard – are currently on gardening leave from UBS’s wealth management business. Vestra is due to open for business on Monday.

Nervous wealth management clients are thought to have left the Swiss bank in droves since it revealed more than $37 billion (£18.6 billion) of writedowns on structured credit products, dismissed its chairman and undertook two rights issues.

UBS said yesterday: “This legal action is to ensure that certain senior departing employees abide by the contractual obligations that they agreed to when they joined UBS and to defend UBS’s legitimate business interests.”

The injunction is a forerunner to a larger legal action against Vestra, in which UBS is expected to accuse the fund managers of conspiring to poach the bank’s business.

Today’s request for an injunction is intended to freeze Vestra pending the full case, which is expected to come to court in the autumn. So-called springboard injunctions, such as the one that UBS is seeking, can be sought against former employees suspected of trying to gain an unfair head start in launching a new business. Such cases usually involve allegations of the misuse of confidential information.

Fifty-two wealth management staff resigned from UBS on May 19 to join Vestra, which was set up by Mr Scott after he left UBS last year. Most of the staff involved in Vestra previously worked in Laing & Cruikshank, the stockbroker bought by UBS in 2001.

This is the second time UBS has faced a fight to keep clients from former Laing staff. Michael Kerr-Dineen, who sold Laing to UBS, left the investment bank in 2006 with 50 colleagues to start Cheviot Asset Management. Cheviot last month offered to take over some of UBS’s British clients in return for a share of the revenues, after UBS struggled with staffing in the wake of the Vestra defections. UBS declined that offer.

Last month Cheviot reportedly sent a letter to former Laing clients, commenting on UBS’s well-publicised problems in the credit crunch and saying that the Swiss bank no longer offered them the security that it once had.

More than 3,000 UBS clients are believed to have switched to Cheviot. UBS’s wealth management division manages assets of £4.6 billion and has about 300 wealth managers in London.

Today’s hearing will not assess the wider argument between Vestra and UBS. Instead, the judge will weigh up the balance of harm to UBS of losing further clients against the harm to Vestra of not being allowed to woo the bank’s customers. Vestra is likely to argue that, as a start-up, such a restriction could severely damage its business.

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