New research by three physicists has raised concerns over the safety of the Large Hadron Collider (LHC), which is due to restart this summer.

Concerns had already been raised that the activities within the 27km particle accelerator could create black holes, which could in turn destroy the planet.

A lawsuit was even filed to prevent the LHC from operation which sparked ribaldry from internet users.

CERN, which operates the LHC, commissioned an extensive study which concluded that, if black holes were formed by the LHC, they would last for only milliseconds before extinguishing themselves.

However, a new study by Roberto Casadio of the University of Bologna, and Sergio Fabi and Benjamin Harms of the University of Alabama, has concluded that the black holes could survive for more than a second.

"While the growth of black holes to catastrophic size does not seem possible, it remains true that the expected decay times are much longer than is typically predicted by other models," the physicists state in a brief paper posted at the scientific discussion website ArXiv.org.

The danger would occur if the black holes stayed in existence long enough to absorb material and become self-sustaining, but the physicists say it is more likely that they would either collapse or stabilise at a very small level and drift out into space.