UBS is in talks to buy a multi-million dollar stake in Bank of China, the country's third-largest lender, in a move that could increase the Swiss group's chances of winning a coveted advisory mandate for BoC's $3bn-$4bn overseas listing.

UBS and other European and US rivals will today begin “pitching” their credentials to BoC's senior management in a bid to win a role on one of Asia's highest-profile deals of the past few years.