Sri Lanka will cut international direct dialling to 13 countries next week in a bid to stop "modem hijacking" and Internet **** scams, the country's telecommunications regulator said on Sunday. The main international gateway operator, Sri Lanka Telecom, was asked to halt direct dialling to the 13 nations on Tuesday after complaints that subscribers were billed for long-distance calls they never made. Aruna Amarasekara, director-general of the Telecommunications Regulatory Commission of Sri Lanka, said the blockage will be in force for three months but subscribers could still make operator-assisted calls if necessary. "We have decided to do this because of modem hijacking," Amarasekara said. He said local subscribers were also advised to block international access on their telephones to prevent unauthorised dialling by malicious programmes, or diallers, installed by some websites. Some websites surreptitiously install diallers on a surfer's computer and use the phone connection to dial long-distance telephone numbers, running up huge bills, he said. Some calls terminate at **** sites. Sri Lanka has found that most of the unauthorised calls terminated in the Solomon Islands, Vanuatu, the Cook Islands, the Wallis and Futana Islands, Papua New Guinea, Nauru, Tuvalu, Tokelau, Western Samoa and Kiribati.