Mercer, the investment consultancy, has added its voice to those urging the owners of large pools of capital - pension funds and the wealthy - to fill the gap left by banks' continued reluctance to lend out big sums to businesses.

The public backing by Mercer, which is one of the world's biggest investment advisory firms, is significant in the context of the $1 trillion (€819bn) of debt that companies need to borrow in the next five years, to replace existing borrowings falling due.