Japan's March tsunami was a wake-up call for Indian Ocean nations still restoring their coastlines after a massive wave struck in December 2004, an expert said Thursday.

"This year's tsunami heightened awareness among all MFF countries that they are still vulnerable," said Donald Macintosh, senior adviser to a group called Mangroves for the Future (MFF).

"It was a wake-up call, a reminder not to be complacent and to look again at how much progress has been made and assess if they need to do more," Macintosh told AFP.

MFF, supported by United Nations and other agencies, promotes and funds projects to plant mangroves on vulnerable coastlines as a defence against tsunamis and typhoons.

Macintosh spoke this week at a conference in the South Korean city of Incheon organised by the International Union for the Conservation of Nature, which has called for "nature-based solutions" as Japan rebuilds.

MFF works to safeguard all coastal ecosystems. It adopted mangroves as a flagship project because of the important role they played reducing the impact of the 2004 tsunami, which killed more than 220,000 people.

"Coastal forests, whether pine or mangrove, won't stop these destructive forces but will reduce them," Macintosh told AFP.

"The force of a wave of up to 6-7 metres (20-23 feet) can be significantly absorbed by a mangrove forest, and a wave of up to five metres by a pine forest."

Mangroves also absorb wind forces which do much of the damage associated with typhoons, and provide a natural habitat for fish, shrimp and crab, he said.

"The Japan tsunami has made all countries more aware of the risk of another tsunami," Macintosh said.

"For example the Seychelles, which feels that it is little better prepared now than in 2004, has requested advice from MFF on disaster preparedness."

Since 2004 MFF has focused on Thailand, Indonesia, Sri Lanka, the Maldives, India and the Seychelles. Pakistan and Vietnam have also joined, and Bangladesh, Cambodia, Myanmar and East Timor will join in the future.

The group has offered Japan advice and help based on its experience of the 2004 tsunami. But Macintosh said it was more appropriate for Japan to plant pine forests rather than mangroves, given its climate.