The Geneva-based private bank run by Guy de Picciotto, the son of the founder, hopes the deal will bolster business in Asia, a particular focus for wealth managers as the region is the fastest production line for multi-millionaires and billionaires.

In an initial step, UBP told staff on Thursday it would take on between 290 and 340 people from Coutts out of an overall 450 in Europe, the Middle East and Africa (EMEA), the person said.

Coutts' EMEA operations are mainly based in Switzerland, but it also has operations in Monaco and Dubai.

A spokesman for Coutts confirmed the news to Reuters.

Of the staff taken on by UBP, up to 150 will be responsible for winding down the Coutts International unit, expected to conclude by the end of 2017.

Staff targets for Coutts' Asian operations, which employ roughly 400 people, will follow in a separate step next month, the person said, but are not expected to be as severe as in EMEA because UBP has a limited Asian presence.

UBP currently has assets under management of around 98.7 billion Swiss francs ($105.1 billion), compared with around 30 billion francs for the Coutts unit.

UBP expects to take on between 60 to 70 percent of client money held by the unit of Coutts, which was founded in the 18th century and is best known as banker to Britain's Queen Elizabeth.

(Reporting by Katharina Bart and Oliver Hirt; Editing by Mark Potter)