Singapore is planning to regulate the sale of pre-paid mobile phone cards following evidence terrorists have used them to help carry out attacks, Home Affairs Minister Wong Kan Seng revealed.

Singapore's Internal Security Department has found that the Sri Lankan separatist group Liberation Tigers of Tamil Eelam and the Southeast Asia-based Jemaah Islamiyah "made extensive use" of mobile phones loaded with pre-paid cards, Wong said Thursday.

Evidence that mobile phones have been used to remotely trigger explosives have been uncovered in several major terrorist attacks worldwide, including last year's Madrid train blasts.

The use of pre-paid cards is popular because it allows the user anonymity as there is no contract with the service provider.

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