BANGKOK - INDONESIA'S coral reefs damaged by the 2004 tsunami are recovering rapidly, helped by natural colonisation and a drop in illegal fishing, scientists said on Friday.

Surveys taken after the Dec 26, 2004 disaster showed up to a third of reefs were damaged and experts predicted it would take a decade for full recovery.

Scientists from the New York-based Wildlife Conservation Society said their examination of 60 sites on 800km of coastline along Indonesia's Aceh province showed the reefs were bouncing back.

'On the 4th anniversary of the tsunami, this is a great story of ecosystem resilience and recovery,' said Mr Stuart Campbell, coordinator of the Wildlife Conservation Society's Indonesia Marine Programme.

'Our scientific monitoring is showing rapid growth of young corals in areas where the tsunami caused damage, and also the return of new generations of corals in areas previously damaged by destructive fishing,' Mr Campbell said in a statement.

'These findings provide new insights into coral recovery processes that can help us manage coral reefs in the face of climate change.'

A massive earthquake off Sumatra in December 2004 triggered a tsunami that killed more than 230,000 people along the Indian Ocean coastline - more than half in Indonesia.

Reef studies after the disaster found up to 30 per cent of reefs were damaged in Indonesia, Thailand, India and Sri Lanka. The study predicted they would recover in 10 years, but much depended on efforts to control illegal fishing, pollution and coastal development.

In the case of Aceh, Mr Campbell said communities have responded to the maritime conservation calls to protect the reefs. Fishermen have stopped using illegal techniques like dynamite and villagers have transplanted corals into areas that were hardest hit.

'The recovery, which is in part due to improved management and the direct assistance of local people, gives enormous hope that coral reefs in this remote region can return to their previous condition and provide local communities with the resources they need to prosper,' Mr Campbell said.

Professor Ove Hoegh-Guldberg, a reef expert from the University of Queensland who did not take part in the study, said the findings were not surprising since corals typically will recover if not affected by fishing and coastal development.

'The mechanical damage from the tsunami left a whole bunch of shattered corals on the bottom of the sea,' Prof Hoegh-Guldberg said.

'Left alone, these things can quickly grow back into what looks like a coral reef in a short time,' he said. 'We are seeing similar things around the southern Great Barrier Reef where reefs that experience major catastrophe can bounce back quite quickly.' -- AP