It is the machine that scientists hope will recreate the conditions present at the beginning of time. But scientists at the £3.6bn Large Hadron Collider (LHC) found their plans to emulate the big bang postponed this week when a passing bird dropped a "bit of baguette" into the machine, causing it to overheat.

Cern, the European particle physics laboratory, launched the LHC with much fanfare on 10 September last year. Physicists hope to use the collider to prove the existence of the Higgs boson, or God particle, which gives matter in the universe its mass.

But the collider, which when running will collide protons travelling at 99.9% of the speed of light, has been out of action for over a year after a helium leak caused it to be shut down on 19 September 2008, nine days after its start-up.

The particle accelerator, which is buried 100m underground near Geneva, is currently undergoing tests ahead of its proposed restart date later this month, but the testing process was stopped on Monday after the power supply to the collider was cut.

A Cern spokeswoman, Christine Sutton, said scientists had headed above ground to investigate when they made their discovery.

"The problem related to the high voltage supply," Sutton said. "We get mains voltage from the grid, and there was an interruption in the power supply, just like you might have a power cut at home. The person who went to investigate discovered bread and a bird eating the bread."

Sutton said the bird and its bread were discovered at a compensating capacitor – one of the points where the mains electricity supply enters the collider from above ground.

The incident cut power to one of the collider's cooling plants, causing temperatures to rise by more than 3C in part of the tunnel.

Superconducting magnets within the LHC require a temperature of 1.9C above absolute zero (-273.15C) to steer, and ultimately collide, particles around the 16.8 mile (27km) circuit.

This latest incident, although far less severe, appears to bear some similarities to the fault that caused the LHC to shut for more than a year after its launch. On that occasion faulty wiring led to an electrical failure, causing a rise in temperature which led to helium, cooled to minus 271C, being released into the machine.

The 2008 fault damaged a 400 metre stretch of the collider and cost Cern £23m. Scientists had to redesign safety systems to prevent a repeat, a process which has taken over a year.

However in this latest incident the magnets were only stopped for three days, while the LHC could be recooled, and Sutton said the power cut did not pose a risk to either life or the future of the project.

"The beams [of protons] would have been dumped, we have very safe mechanisms that come instantly into play," she said.

"They deposit beams into a huge block of graphite which is cooled to take up the energy of the beam. This is something Cern has a lot of experience of, perhaps power cuts will usually be caused by a more obvious kind of interruption than a bird eating a baguette – particularly by lightning, for example, but these incidents will happen."