Moscow (AFP) - Russian President Vladimir Putin on Wednesday rubbished European calls to reduce reliance on fossil fuels, saying that such ideas could lead to humans living in caves again.

Speaking at an investment forum in Moscow, Putin also slammed shale gas production through fracking as dirty and environmentally damaging, saying Russia -- one of the world's top gas producers -- would never use this technology.

Asked what he thought of Europe's moves to reduce use of gas, for which it is heavily dependent on Russia, Putin said that "in my view, disdaining such a clean hydrocarbon as gas is absolutely strange".

The European Union's investment arm last week said it would stop funding fossil fuel projects -- including gas -- from 2022.

"When people suggest such ideas, I think that mankind could end up back in caves again," Putin saod.

The Russian president said that "the way technology is today, without raw hydrocarbons, without nuclear power, without hydroelectric power, mankind can simply not survive, cannot preserve its civilisation".

He boasted that Russia's relatively intense use of gas and hydroelectric power had an energy balance that is "one of the greenest in the world".

The extraction of shale gas through fracking -- banned in many countries but booming in the United States -- is "without any exaggeration barbaric", Putin said.

The extraction techniques "destroy the environment", he said. "In some places where shale oil is being extracted, people don't have water coming out of their taps, but black slush.

"Despite all the possible economic advantages, we don't need such extraction, we won't do this ever."