A plan to build the world's most powerful optical telescope, able to scour the heavens for planets that could sustain life, has cleared an important hurdle, the European Southern Observatory (ESO) said.

Two-thirds of ESO's governing council approved the so-called European Extremely Large Telescope (E-ELT), which opens the way to starting work on the project, the consortium announced late Monday.

The 1.083-billion-euro ($1.35-billion) scheme entails building a telescope with a massive light-catching mirror 39.3 metres (127 feet) wide, several times the size of the biggest optical telescopes today.

It will be sited on Cerro Armazones in northern Chile, close to ESO's existing Paranal Observatory, where the extremely arid conditions and high altitude -- 3,060 metres (9,945 feet) -- offer excellent viewing of the skies.

Paranal already hosts the Very Large Telescope (VLT), comprising four highly advanced telescopes each with mirrors of 8.2 metres (26.65 feet) across.

"This is an excellent outcome and a great day for ESO. We can now move forward on schedule with this giant project," ESO's director general, Tim de Zeeuw, said after the council meeting in Garching, Germany, on Monday.

If all goes well, the E-ELT will start operations about a decade from now, becoming one of the astronomical assets of the 21st century alongside a vast radio telescope, the Square Kilometre Array (SKA) set to be built in South Africa and Australia.

Mirror size in a telescope determines how much light can be snared. A bigger mirror means more distant and smaller stars can be observed.

The E-ELT will gather 100 million times more light than the human eye, eight million times more than Galileo's telescope which saw the four biggest moons of Jupiter four centuries ago, and 26 times more than a single VLT telescope.

"The E-ELT will tackle the biggest scientific challenges of our time, and aim for a number of notable firsts, including tracking down Earth-like planets around other stars in the 'habitable zones' where life could exist -- one of the Holy Grails of modern observational astronomy," ESO said.

ESO, which marks its 50th anniversary, is Europe's biggest intergovernmental venture in astronomy.

In Monday's vote, six out of 10 countries gave firm approval and four gave "ad referendum" approval, meaning that they needed an official green light from their governments.

Four other countries said they supported the scheme and were "actively working towards joining the programme in the near future," ESO said.

Work on building the E-ELT will start once the "ad referendum" votes are made official and financial commitments are secured for at least 90 percent of the total cost.