In the face of stern questioning by some in Congress over whether enough was done, the head of the National Oceanic and Atmospheric Administration said his agency did all it was responsible for doing in warning 26 countries in the Pacific.

''We cannot watch tsunamis in the Indian Ocean,'' said Conrad C. Lautenbacher, the Commerce Department's undersecretary for oceans and atmosphere and a retired Navy vice admiral, noting that no warning system exists for all 11 countries where the death toll has now topped 117,000.

''Folks out there tried to contact people that they thought would be interested. ... They did what they thought at the time were the most prudent things to do,'' he said. ''If we can improve it, believe me, we will improve it.''

In an interview with The Associated Press, Lautenbacher said he had ordered an internal review of its response to the quake and tsunamis. He said he also has asked NOAA staff to look at creating a ''rapid reaction'' emergency team and a more global warning system.

Lautenbacher said the chances of a major earthquake in the Atlantic Ocean ''are small, but they're not zero.''

''There is the potential of tsunami damage'' in the Caribbean, he said, ''and we believe that (warning) coverage should be extended to those areas as well.''

In the past 150 years, the Caribbean has had more than 50 tsunamis and the Atlantic more than 30, about half off the U.S. and Canadian coasts but none since 1964, NOAA figures show.

Some scientists had urged both the Clinton and Bush administrations to create a tsunami warning system in the Atlantic and the Caribbean, but they say nothing much happened.

''One option we explored as recently as a few months ago was to ask for money to have the seismic network at the university here become a 24-hour operation. ... But again there is no money,'' University of Puerto Rico oceanographer Aurelio Mercado-Irizarry said Thursday from Mayaguez.

''Based on the magnitude of what happened in the Indian Ocean, I think something must be done, but at what level and what expense is the question,'' Mercado-Irizarry told the AP.

A huge earthquake off Lisbon, Portugal's coast in 1755 generated tsunamis that crossed the Atlantic and wreaked havoc in the Caribbean and the West Coast of Africa, he said.

Lautenbacher might be called to testify about the U.S. response to the tsunamis and what can be done to beef up warnings for the Caribbean and Atlantic regions before the Senate Commerce Committee's oceans, fisheries and Coast Guard subcommittee.

Fifteen minutes after Sunday's quake near Sumatra, NOAA fired off a bulletin from Hawaii to 26 Pacific nations that now make up the International Coordination Group for the Tsunami Warning System, alerting them of the quake but saying they faced no threat of a tsunami.

Fifty minutes later, the U.S. agency upgraded the severity of the quake and again said there was no tsunami threat in the Pacific, but identified the possibility of a tsunami near the quake's epicenter in the Indian Ocean.

After nearly another half hour, NOAA contacted emergency officials in Australia as a backstop, knowing they would quickly contact their counterparts in Indonesia. It wasn't until 2½ hours after the quake that NOAA officials learned from Internet news reports that a destructive tsunami had hit Sri Lanka.

''The fact that the potential danger rose to the level of prompting a swift warning to two nations, while others could be faced with a potentially devastating impact, raises serious questions,'' the Senate oceans subcommittee chair, Sen. Olympia Snowe, R-Maine, said in a letter to Lautenbacher.

Lautenbacher said there was only so much NOAA can do.

''The system is set up for the Pacific, and it is resourced and it is staffed to operate for the Pacific. It is not resourced or staffed to do the world,'' he said.

Among the 11 nations reporting deaths, only Indonesia received any warning from NOAA, and then only indirectly through Australia. After reports of casualties in his country, a Sri Lankan Navy commander called the Hawaii warning center to ask about the potential for more tsunamis. The U.S. ambassador in Sri Lanka also called the center asking to be notified of any big aftershocks.

Meanwhile, India's science and technology minister requested an investigation into a report that his country's air force base was told of a massive quake an hour before the tsunami hit its southern shore but disaster officials were notified too late to take action to protect people.