Washington - US space agency NASA does not have enough cash to track the large nearby asteroids that could pose a hazard to Earth, a study by the National Academy of Science found Wednesday.

In 2005, Congress ordered NASA to track up to 90 per cent of near- Earth asteroids that are 140 metres in diameter or larger by 2020. But no money was budgeted for the task, making it impossible to complete.

The report also said astronomers are capable of tracking the asteroids if given enough resources to do so.

Scientists estimate that around 100,000 asteroids and comets are located near Earth, with about 20,000 in danger of impacting Earth. (dpa)