The Swiss foreign ministry says at least nine Swiss citizens were among those killed in Sunday’s earthquakes in southeast Asia.
Officials estimate the overall death toll in one of the worst natural disasters will reach more than 66,000.
Swiss Foreign Minister Micheline Calmy-Rey said on Tuesday that the nine Swiss victims included six in Thailand, two in Sri Lanka and one in India.
She added that the death toll was likely to rise, but gave no further details.
Around 2,200 tourists from Switzerland are believed to have been in the disaster region when the giant waves hit the shores.
The ministry said about 800 Swiss had contacted the authorities as of Tuesday, but there had been no news from another 1,700 Swiss citizens travelling or living in the region.
Medicine and logistics
The Swiss Agency for Development and Cooperation (SDC) said it was sending an additional team of experts and medical equipment to the island resort of Phuket in Thailand.
The specialists will coordinate the repatriation of Swiss tourists and also help identify further Swiss victims.
Other teams of medical and logistical experts are working in Sri Lanka and southern India.
Officials said 15 Swiss experts were cooperating closely with local authorities.
Meanwhile the Swiss Air Rescue Service (Rega) has sent a second ambulance jet with medical teams to Phuket.
A spokesman said Rega was providing medical assistance to about 100 injured Swiss tourists in the region.
At least 17 Swiss citizens are still missing.
Swiss tour operators said they feared that many Swiss tourists could be among those killed in Phuket and Khao Lak.
A senior foreign ministry official said more funds were needed for the tens of thousands of people affected by the tremor in southeast Asia.
On Sunday the government released SFr1 million ($900,000) for emergency aid and rescue operations.
Swiss Solidarity, the fundraising arm of the Swiss Broadcasting Corporation, said on Wednesday that it had already received more than SFr4 million in donations.
A special nationwide fundraising campaign is due to take place on January 5.
Donations can be made over the internet and at post offices in Switzerland (account: 10-15000-6).
More than 20 countries have pledged emergency aid worth more than $60 million.
Several Asian nations have sent naval ships carrying supplies and doctors to devastated areas.
The United Nations said the disaster was unique in the way it had affected such a large area and so many countries, and would require the biggest and costliest relief effort in its history.
swissinfo with agencies
Officials say more than 66,000 people have died in Sunday's undersea quake in southeast Asia.
The Swiss foreign ministry has confirmed nine Swiss victims, but warned that the death toll was likely to rise.
The authorities are continuing to locate and repatriate Swiss victims in the region.
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