For Asian governments, text-messaging is no longer a matter of twiddling their thumbs.

Asia is cracking down on a technology that has become a powerful social tool, used to organise mass protests, sow wild rumours, perpetrate crime and, it is feared, trigger bombs.

From Southeast Asia, where authorities say they are motivated by security and public-nuisance concerns, to China, where scams and spam seem to be the major worry, text-messaging by anonymous mobile-phone users has caused a huge, ringing headache.

In the developing countries of Asia, most mobile-phone users are faceless because they use pre-paid phone cards, which can be bought for a few dollars without giving a name and address.

But anxious governments are changing all that.

This month, Malaysia ordered phone companies to register all holders of pre-paid services after text-messaging gossip-mongers hit a raw nerve with false talk that the premier's ailing wife had died.

The rumour grew so large, he felt compelled to deny it.

Thailand moved to register users of pre-paid phones in May.

Shanghai, China's richest city with 20 million people, will require registration of pre-paid users from this month to tackle text-message fraud. Last year, Taiwan also sought to identify pre-paid phone users.

In Japan, there's a lot of pressure from within the industry to clamp down on pre-paid because it's a way for criminal gangs to communicate.

Few countries know the power of text-messaging better than the Philippines, where a lightning campaign rallied hundreds of thousands of people on to the streets in 2001 in a "people power" uprising that ousted President Joseph Estrada.