A program set up by NASA to monitor "near-Earth objects" (NEO) a decade and a half ago has so far been able to track less than 10,000, which means that the vast majority of the asteroids are still hidden.
Most of the larger specimens that can wipe out entire continents, have been found but smaller asteroids like 2012 DA14 is powerful enough to destroy an entire city if they plunged down to Earth, the Telegraph reported.
Now experts are calling for greater monitoring of small NEOs measuring less than a kilometre across, and for a contingency plan in the event of a likely impact.
UK Space Agency engineers visited the United Nations this week to seek a deal with colleagues from around the world and hope to come to an agreement before Friday.
Their first goal is to secure funding for asteroid monitoring from countries other than the US - currently the only nation carrying out such a program.
This would allow new systems to be built specifically to find smaller asteroids, and open up more facilities across the world to help in the search.
As well as increasing the monitoring of NEOs, the UN group hopes to make progress on an emergency plan detailing measures to be taken if an asteroid does become a threat to Earth.
Even if an agreement is reached, experts have claimed that it will be many years before they have a full idea of the asteroids, which can threaten the Earth, and when.