More than $48 trillion must be invested by 2035 to meet global energy needs as current technologies go offline and demand rises in emerging nations, the International Energy Agency (IEA) said in a report launched in London on Tuesday.

Pump jacks are seen at dawn in an oil field over the Monterey Shale formation near Lost Hills, California, on March 24, 2014.

The Paris-based body predicted that $2 trillion per year will need to be invested by 2035, a rise of $400 billion from 2013, while annual spending on energy efficiency will have to increase to $550 billion.

"This amounts to a cumulative global investment bill of more than $48 trillion, consisting of around $40 trillion in energy supply," it explained.

Most of the $40 trillion is needed to offset declining production from existing oil and gas fields and to replace power plants and other assets that will reach the end of their productive life.

The main components of energy supply investment would be $23 trillion in fossil fuel extraction, transport and oil refining; almost $10 trillion in power generation, of which low-carbon technologies account for almost three-quarters, and a further $7 trillion in transmission and distribution, it added.

The autonomous agency, responsible for promoting energy security, warned policymakers that they faced conflicting needs.

Demands for stronger action on climate change could cause a backlash against the cost of subsidies to renewables and calls for lower energy prices could come up against public opposition to cheaper extraction techniques such as fracking.

"Against this backdrop, there is a risk that policymakers fail to provide clear and consistent signals to investors, with particular impacts on low-carbon technologies that depend, for the moment, on policy support," said the report.

The IEA urged for new forms of investment to be exploited, and suggested that institutional investors, such as pension funds and insurers, could be vital as a source of long-term funds.

It also predicted that oil investment would shift towards the Middle East as non-OPEC supplies run out, and that gas prices around the world should converge given the boom in investment.

"Investment in liquefied natural gas (LNG) facilities creates new links between markets and improves the security of gas supply," it explained.

But "high costs of gas transportation may dampen the hopes of LNG buyers in Europe and Asia for much cheaper gas supplies."

Europe was singled out as a particular concern, requiring $2 trillion in power sector investment by 2035, while India will need $1.5 trillion in power sector investment over the same period to support its growing economy.