The huge particle collider built to simulate the conditions of the "Big Bang" will not restart until spring 2009 after a weekend technical glitch, the European Organisation for Nuclear Research (CERN) said on Tuesday.

A helium leak into the tunnel housing the biggest and most complex machine ever made forced CERN to shut down its Large Hadron Collider (LHC) on Saturday, just 10 days after starting it up.

CERN Director-General Robert Aymar said this was a psychological blow after a successful start of the LHC following years of painstaking preparation by skilled teams of scientists.

"I have no doubt that we will overcome this setback with the same degree of rigour and application," he said in a statement.

The most likely cause of the leak of helium into the LHC's 17-mile (27-km) tunnel under the French-Swiss border was a faulty electrical connection between two of the accelerator's giant magnets, CERN said.

For a full understanding of the incident scientists must now raise those sectors of the tunnel back to room temperature from its operating temperature of minus 271.3 degrees Celsius (minus 456.3 degrees Fahrenheit) and open the magnets for inspection, a process taking 3-4 weeks.

This investigation and repairs, followed by CERN's winter maintenance period, will push back the restart of the accelerator complex to early spring 2009, CERN said.

CERN will then resume sending beams of particles around the tunnel, as it did successfully after starting up the LHC on Sept. 10. The next step is to smash beams travelling in opposite directions into each other at nearly the speed of light.

This would attempt to recreate on a miniature scale the heat and energy of the Big Bang, the explosion generally believed by cosmologists to be at the origin of our expanding universe.

At full speed the LHC will engineer 600 million collisions every second of subatomic particles called protons, which will explode in a burst of new and previously unseen types of particles.

The experiment could confirm the existence of the Higgs Boson, a theoretical particle named after Peter Higgs who first proposed it in 1964 as a way of explaining how matter has mass.

CERN, which has had to dismiss suggestions that its experiment could create tiny black holes of intense gravity that could swallow up the whole of planet Earth, says there was never any risk to people from the malfunction.