The anniversary of the tsunami was marked today in countries around the Indian ocean.

At least 12 different countries were affected by the tidal wave, which followed an ocean earthquake just off Indonesia.

An estimated 224,000 people died following the tragedy on 26 December 2004.

Indonesia mourned the victims of the disaster as thousands of people converged on mosques and mass graves to chant prayers and lay flowers.

The Indonesian president, Susilo Bambang Yudhoyono, led a ceremony at Banda Aceh that began with a minute's silence.

The president turned on a wailing siren, symbolically activating an early warning system being set up to prevent a repeat of the tragedy.

Sri Lanka's President, Mahinda Rajapakse, brushed aside security fears to lead the national remembrance effort with a two-minute silence.

The tsunami had initially raised hopes of a peace deal with the rebel Tamil Tigers but Colombo and the guerrillas, who each control part of the devastated coastline, could not even agree on a mechanism to share $3.2bn in foreign aid.

Thailand's Prime Minister, Thaksin Shinawatra, led his nation in mourning during a beachside ceremony at Khao Lak, where he laid the foundation stone for a tsunami memorial.

In India, on the island of Car Nicobar, the military unveiled a memorial to 119 air force fliers and their relatives who died when the waves overran the two-storey living quarters of the Indian Air Force base there.

Sweden, which suffered more deaths in the tsunami than any nation outside Asia, remembered the 543 of its people who died.

Official ceremonies were held in the capital Stockholm and in the southern cities of Gothenberg and Malmo.

Ahern: Lessons to be learned from tsunami

The Taoiseach, Bertie Ahern, has said lessons must be learned from the way in which governments respond to crises around the world.

Mr Ahern said it was important for the international community to examine the effectiveness of its response to disasters.

He said all should be remembered including the Irish victims, Lucy Coyle, Éilís Finnegan, Conor Keightley and Michael Murphy.

Mr Ahern said Ireland's contribution to the relief fund for the Asian tsunami placed it among the most generous nations on earth.

Ireland had contributed more than €100m to the recovery effort, he said, €20m of which came from the Government with the remaining €80m from private voluntary contributions.