"Private investment frees up governments to focus on the most difficult projects while the more straightforward but important ones can be funded by the private sector," she told a Fitch forum on infrastructure financing in developing countries.
"It could maybe accelerate the process of infrastructure development if many entities support different infrastructure projects at the same time," Howells said.
"We know from experience elsewhere in the world that governments can't do it all," she said.
Howells acknowledged that it may be cheaper for sovereigns to borrow and finance projects in the early phase of a country's infrastructure modernisation but noted private financing may be needed later on.
"The global experience is that governments can