Up to ten Irish people are being treated for injuries and two women are reportedly missing in Thailand after the tsunami which killed an estimated 55,000 people in South East Asia.
They are among up to 500 Irish people caught up in the tsunami that wiped out thousands of communities in South East Asia.
A Department of Foreign Affairs spokesman was unable to confirm reports that two Irish people who were holidaying on a Thai island are missing.
He said Government representatives in Thailand and Sri Lanka were contacting every Irish citizen living in or visiting the countries devastated by the catastrophe.
Officials are liaising with other embassies in the Indian Ocean region to find out if any Irish nationals were missing, the Minister for Foreign Affairs, Mr Ahern said.
"There are approximately five to 10 people who are receiving medical care but it's a bit difficult to estimate what the situation is because most of these countries don't require a visa," he said.
"From the calls we are getting - we got 1,000 calls to lines over the last 24 hours - we estimate there is about 500 people in the affected areas altogether."
There have been no reports of any Irish fatalities so far. A dedicated helpline manned by staff from the Department of Foreign Affairs has been set up on (01) 4082308.
It could be several days before officials know the exact number of Irish people affected due to poor telecommunications in many of the areas.
People planning to travel to other tourist resorts in the region have been advised to check with travel operators before setting off.