Washington-based management consultancy, Futron, calculates that the loss of the ISS in any eight-month period lies between one in 200 and one in 500.

Futron presented its risk assessment in a report to the US National Aeronautical and Space Administration (NASA).

This means "there's a five- to 10-percent chance of disaster over 15 years," the British weekly New Scientist reports in its December 25 issue.

"Its calculations suggest that, if this happens, there is a 93-percent probability that a micrometeorite impact will be the cause," the article said.

Only two percent of the risk would come from fires, explosions or collisions between spacecraft, according to Futron's calculations.

The consultancy added that the ISS' controllers could expect at least one "loss of a crewmember" over the next 15 years -- a category that includes death as well as illness or an accident requiring evacuation of an astronaut.

Futron admits its analysis is preliminary, and based on the calculation of risk faced by a station crewed by three astronauts, halfway through construction. These figures were then extended to cover a 15-year period.

But experts already contest Futron's approach, not least because it suggests that accidents inside the station will be a greater risk to the astronauts than space walks, New Scientist said.

This is surprising, given that astronauts will have to carry out an unprecedented amount of space-walking to put the ISS together.

They also query the assumption about micrometeorites, noting that the now defunct Soviet/Russian space station Mir had little problem with collisions with material from space, but was several times imperilled by fires or computer crashes.

Micrometeorites are tiny particles, often no bigger than a speck of dust, that are part of the cosmic debris hurtling through space.

The huge speed at which they travel could cause them to damage equipment or even perforate the ISS' hull.

The ISS, a partnership of 16 countries, is being assembled from modules under a 40-flight schedule over the next five years.

Since November 1998, two modules have already been connected -- the Russian-built Zarya and the US-built Unity -- and a US shuttle mission in June this year supplied them with tools and cranes.

When completed, the ISS will have an internal volume roughly equivalent to that of the cabin of a 747 jumbo jet. It will be inhabited by an international crew of up to seven, living and working in space for between three and six months at a time.