The amount of money invested in the infrastructure debt market could be set to double in the next two years, according to analysts Preqin, with 13 fund managers currently on the road seeking to raise money from investors and plug the gap in financing left by banks' reluctance to lend.

As a result of the dearth in banking lending, infrastructure equity funds raised by fund managers and banks and others - typified by Goldman Sachs' giant $6bn fund, GS Infrastructure Partners - have found it more difficult to borrow.