The Tidal Wave Rescue Centre said it was flooded with calls and text messages after sending out alerts to those using international roaming phones in the island to register their presence, spokesman Chris Dharmakirti said.

The Hong Kong-based risk consultancy firm, Hill and Associates, said they made use of the rescue centre facilities and were able to locate at least 30 foreigners from the devastated areas of Sri Lanka.

"We extracted at least 30 foreigners from two of our corporate clients," Hill and Associate spokesman Charles Champagne told AFP when contacted by telephone.

Dharmakirti said a group of foreigners rescued using their "cell triangulation" system had been employees of an international investment bank. He had earlier incorrectly identified them as employees of Morgan Stanley.

More than 600 people had been tracked with the use of mobile phones along the devastated areas, officials said.

Thirty six stranded British tourists were rescued early Tuesday thanks to a mobile phone with one of them.

The Britons were picked up from the southern beach resort of Hikkaduwa where they were stranded after the tsunami lashed three-quarters of the island's coastline, killing nearly 17,800 people.

The authorities found there were 10,252 international roaming phones working on Sri Lankan networks at the time of the tragedy, Dharmakirti said.

He said 5,983 roaming phones had gone dead since the disaster while 4,269 phones had been used to make at least one call after the tragedy.

"Whenever anyone used the phone, we could track where the person was and restrict our search to affected areas of the country."

"If a phone is dead it could be that the unit is lost or the person is affected by the tragedy," Dharmakirti said. "But, we are keeping a track on these numbers."

He said they sent instructions to the phone users to call a toll-free local number that will be answered by a call centre manned by some 100 people.

"Some people who called us did not know where they were. All they could say was they were on high ground. But we were able to pin-point from where the call was coming and could rush help," he said.

The mobile phone networks too were knocked out after Sunday's tragedy, but 90 percent of the services were restored quickly by arranging mobile generators to power base stations.

"This is the first time in Sri Lanka that we have used high tech call tracking for a rescue mission," he said.

He said people abroad could call two numbers to get information about survivors who made contact with the rescue centre. When dialling from abroad, the number is +94-11-2395230 or 94-77-3166999.

From within the country, the number to dial is 011-2395227 or from any mobile phone in the country the toll free number to call is 112.

He said they were also operating a web site www.travelsrilanka.com to collect information on missing persons to try and locate them using the mobile phone network.

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