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 13,000 people.

A private initiative involving all phone companies here began monitoring mobile phones with international roaming and traced the call patterns to figure out the location of the phone users.

"There were 10,252 international roaming phones working on Sri Lankan networks at the time of the tragedy," Chris Dharmakirti, who is heading the Tidal Wave Rescue Centre said. "We sent everyone an sms and got responses from

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.

"Last night we had a response from a British tourist and based on tracking his call we were able to locate a total of 36 stranded Britons," Dharmakirti said. "Four of them were critically wounded, but we managed to get to them to safety."

Another 35 Hong Kong-based employees of Morgan Stanley, leading investment bankers, who were in southern Sri Lanka were tracked down because of their international roaming phones that continued to be switched on.

"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. It has been highly successful and the teenagers who manned the call centre were themselves keen to go out and help victims," he said.

"What we are doing is to use this to help any survivor who is marooned and needs help."

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 there was more information on the rescue centre website www.travellanka.com.

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