Washington ? U.S. officials had a conference call Sunday to discuss ways to aid the south Asian countries inundated by the Indian Ocean tsunami. A White House statement said aid already had been sent to Sri Lanka and the Maldives.

International organizations began flying humanitarian teams in from Europe despite the holiday weekend, and the British-based poverty relief group Oxfam warned that many more people could die without a rapid response.

“The floodwaters will have contaminated drinking water, and food will be scarce,” Jasmine Whitbread, the group’s international director, said in a statement.

The International Red Cross in Geneva launched a six-month campaign for donations of cash, goods or services totaling $6.7 million. The U.S. fund for UNICEF estimated that one-third of the reported dead were children.

The Web site of the U.S. Agency for International Development, which provides humanitarian assistance abroad, advised that the “most efficient and effective way to help those affected by a disaster overseas is to make a monetary donation to a humanitarian organization that is implementing relief programs in the affected region.”