An alert centre in Hawaii that warns Pacific countries about approaching tsunamis had detected the earthquake that generated killer waves across Asia, but had no way of raising the alarm.

The absence of an alert system in Asia meant the information could not be sent out fast enough to save any of the more than 23,000 lives that were lost in the catastrophe.

"We did what we could to warn Asian nations of the likelihood of a tsunami," said Charles McCreery of the Pacific Tsunami Warning Centre in Honolulu, adding that the centre did not have direct contacts with Indian ocean nations.

The centre, set up by the National Oceanic and Atmospheric Administration (NOAA) in 1949 after a huge wave killed 159 people in Hawaii, tried desperately to warn Asian nations through US embassies in their capitals.

"From our instruments we can detect any large earthquake in the Pacific, usually within two to three minutes of the occurrence of the earthquake, and warn any country that is threatened," he said.

The centre issued a bulletin at 0114 GMT when it detected the temblor off the coast of Indonesia, but with no early warning system in place in Asia, scientists had no choice but to begin working their phones.