For thousands of young Israelis, the sun-drenched archipelagos of Southeast Asia were the perfect destination to forget the rigors of military service.

But this week, that post-Zionist nirvana became a nightmare. The tsunami that swept India, Thailand, Sri Lanka and the Andaman Islands on Sunday plunged hundreds of Israeli families into a frenzy of worry over relatives feared lost while touring.

Israel's Foreign Ministry said Tuesday that witness testimony suggested that at nearly 70 of the approximately 500 Israeli tourists still unaccounted for in hard-hit Southeast Asian nations may have been swept out to sea and drowned. At least 33 Israelis are receiving treatment in hospitals in the region, the Foreign Ministry said.

For thousands of families living in or visiting the Indian Ocean region, Sunday's catastrophe confirmed their worst fears: At least 45,000 people were killed by the devastating earthquake and tsunami, mostly in Indonesia, India and Sri Lanka.

A Belgian Jewish couple reportedly lost their 11-month-old son in the disaster. According to Israel's Ma'ariv newspaper, Matan Nassima's body was found Tuesday near the Thai resort where his family had been vacationing.

Details were not immediately known, but it also was believed that members of the South African, Australian and New Zealand Jewish communities were missing.

Immediately after the tragedy, Israel and Jewish groups swung into action. Israel's Foreign Ministry set aside $100,000 in aid for each of the countries hit by the tsunami. Four top doctors from Israel's Hadassah Hospital were dispatched to Colombo, Sri Lanka, at the ministry's request, Hadassah said. Among them were the hospital's head of general surgery and trauma, its chief of pediatrics and two anesthesiologists.

On Tuesday, Sri Lanka turned down an Israeli offer to send military personnel to help with search-and-rescue efforts but said it would accept a smaller team.

North American Jewish groups also were participating in the relief efforts. The American Jewish World Service (AJWS) was expecting to send its first shipment of medicine Tuesday to Sri Lanka, Indonesia and India. It has been coordinating with 23 partner organizations in the region to assess needs on the ground. The group is hoping to receive donations to cover the cost of emergency supplies.

The American Jewish Joint Distribution Committee is working with its office in Bombay and elsewhere to coordinate relief efforts. The organization is hoping to provide food, water, clothing and shelter to countries affected by the earthquake and tsunami.

Chabad of Thailand responded to the crisis by dispatching a rabbi to Phuket to aid rescue efforts and turned the three Chabad Houses of Thailand into crisis centers where survivors can call home, get a free meal or receive funds for new clothing and medical help.

The Jewish Federation of Greater Los Angeles has established a Southeast Asia Relief Fund. To contribute, call (323) 761-8200, or send a check payable to The Jewish Federation at 6505 Wilshire Blvd., Los Angeles, CA 90048 and write Southeast Asia Relief Fund on the memo line.

For families of potential victims, the waiting for news was excruciating.

At Erez Katran's home in Haifa, a 24-hour vigil was set up next to the telephone in hopes that he would call. His family hoped Katran's silence was due to the fact that he was incommunicado while sailing in the Bay of Bengal. Katran was among the Israelis who remained unaccounted for Tuesday, despite urgent Foreign Ministry efforts to track them down.

In addition to delivering bad news, the Israeli communications industry pitched in with the search efforts. Every major Web site set up a page where pictures of missing tourists could be posted in hope that someone would report their location, and one cellphone company offered its Israeli customers in Southeast Asia 10 minutes of free air time to call home.

JTA staff writer Matthew E. Berger in Washington contributed to this report.