Between 500 and 1,000 massive asteroids cross the Earth's path regularly and any one of them could cause a global catastrophe, space experts warned Tuesday, urging quick preventive measures.

Some 6,000 cosmic objects circulating around the planet are currently known to experts in the field, the Association of Space Explorers (ASE) told a press conference at the UN headquarters in Vienna, where it presented its report "Asteroid Threats: A Call for Global Response."

And of these, up to 1,000 had a diameter of 150 kilometres (93 miles) or more, meaning they could cause major damage to the Earth's surface, prompting fires, tsunamis and ensuing disasters like famine, it said.

The organisation includes some 320 members from 34 countries, all of whom have already been in space.

A research, information-sharing and defence network was thus urgently needed to coordinate a global response to the problem, under the leadership of the UN, it said.

Although it should be possible to predict a collision up to 15 years before it occurs, the technology needed to divert an incoming asteroid has yet to be developed and this will require international cooperation, they said.

The UN Committee on the Peaceful Uses of Outer Space is due to examine the report at its 2009 session on June 3-12 in Vienna.