Twenty years on from the Boxing Day tsunami, a Red Cross director has remembered how the disaster sent shockwaves across Sri Lanka.

Dr Mahesh Gunasekara was working as director of the 200-bed Kanthale Hospital and looking forward to starting a new job with the charity in early 2005.

He said: “Until it happened, we never knew the meaning of the word ‘tsunami’. For us, it was just a Japanese word.”

Dr Gunasekara, 60, had gone to visit his parents when his phone rang on that fateful Sunday morning.

The father-of-two recalled: “I got a call from the hospital saying that a large number of casualties were coming and they wanted me back. I started watching TV and listening to the radio, and only then I realised what it was.

“A lot of people had been injured or drowned, they were lying everywhere in the hospitals. It’s something we had never seen - you can never imagine it.”

A massive 9.1 magnitude earthquake that struck off the west coast of Sumatra, Indonesia, had triggered a series of deadly tsunamis.

More than 230,000 people were killed across 14 countries, with the most fatalities in Indonesia, Thailand, India and Sri Lanka.

An estimated 10,000 British citizens were affected and 149 died, many of them in the beach resorts of Thailand and Sri Lanka. 

Over the following days, Dr Gunasekara and his colleagues treated patients who had been injured while swept along by the powerful waves and others who had inhaled water.

Located around 30km from the coastline, his hospital also had the grim task of coping with an unusually high amount of dead bodies.

He said: “We had to deal with them in a dignified manner and make sure they were given a good send off. Some of them, their whole family was gone.”

Sri Lanka - then in the grip of a civil war that had been raging for 30 years - was left “shocked and stunned” by the disaster, the doctor added.

“It was really emotional," he said. "All of us have been badly affected. We were used to dealing with the bombs, blast casualties, gunshot injuries. But nothing like this.”

Dr Gunasekara took on responsibility for the tsunami recovery operation when he joined the Red Cross, and still works for the charity today as Sri Lankan director general.

The tragedy that unfolded on December 26 2004 shaped his career and triggered a major push for greater preparedness across many developing countries.

British people donated £392million to a Disaster Emergency Committee appeal to help the millions affected, including a record £10 million within one 24-hour period.

Dr Gunasekara said: “It was a big disaster, there’s no question about that. But this culture of preparedness really emerged globally after the tsunami.

“With British donations, we started a fund supporting many Red Cross societies from developing parts of the world to strengthen their preparedness efforts.

“Usually, when there’s a crisis, you respond. But if you are better prepared, you can avert a lot of suffering.”

Annual drills, simulation exercises and greater awareness of tsunamis mean that hopefully many lives would be saved if such a disaster occurred today. 

Dr Gunasekara added:  “We are a very small country, everybody knew someone who was affected by the tsunami. The trauma is still within the country, but you have to move on.”

Richard Blewitt, executive director of international at the British Red Cross said the 2004 Asian Tsunami brought “devastation on a massive scale” and the response “pushed the Red Cross and Red Crescent Movement to the limits of our capacity”.

He added: “The incredible generosity of the British people in donating to our appeal and the DEC appeal was invaluable in helping us to respond and meet people’s immediate needs, including food, water, shelter and healthcare.  

“This generosity also allowed us to provide psychosocial support to survivors, the bereaved and those with family members still missing or waiting to be formally identified. It was so important to be able to be there to help people who had suffered unimaginable trauma. 

“The British Red Cross worked hard to support the Red Cross and Red Crescent National Societies in all the affected countries to help them recover from the disaster and build back stronger. 

“At the core of our work was powering locally led action to rebuild people’s livelihoods and better prepare communities for future emergencies.”