More than six billion text messages were sent by mobile phone over the Lunar New Year holiday, with the medium increasingly being seen on the mainland as an easy, affordable way to keep in touch. But the popularity of the short-messaging system (SMS) has also left the authorities worried that it is being used to spread rumours and reactionary views. The holiday messages reaped 500 million yuan (HK$471.8 million) in total revenue for China Mobile, China Unicom and their subcontractors, according to CCID Consulting, an arm of the Ministry of Information Industry. Last year, telecom companies earned six billion yuan from 95 billion messages sent, up from a profit of 1.5 billion yuan on 15 billion messages in 2001. The medium is popular because it costs only 15 fen to send a message, and technological advances have made them more colourful and easier to use, according to Wang De, a telecom consultant at CCID. 'Everybody's become an editor,' he said. 'They can make their own messages.' Users can add ring tones or pictures, then redistribute the message to multiple recipients. Nanjing college student Ma Yanmin said she sent and received about 30 cheerful messages on February 1, the first day of the Lunar New Year. But in the days following the February 12 Guangdong virus outbreak, which killed at least five and caused 305 others to fall ill, mobile text messages were blamed for inciting panic buying of salt and rice. Yesterday's Wen Wei Po reported that police in Guangdong had arrested five people for using text messages to spread rumours of a provincial water shortage. State media occasionally reports a spate of pornographic messages, and last year police arrested a Falun Gong follower for sending thousands of messages in support of the banned sect. Unlike the Internet, which is controlled by multiple government agencies via filters and routine Web site checks, mobile text messages remain unregulated. Craig Watts, a partner with Norson Telecom Consulting in Beijing, said that because they were seldom used for anything but idle chat, SMS had escaped government attention. 'The idea of SMS and politics mixing has always been out there, but in China so far it's pretty harmless,' Mr Watts said. But he said that because text messages could offer poorer people a cheap way to spread dissent, the climate could change. 'Less enfranchised people have a means to organise,' he said. Eventually, SMS might go the way of China's Internet in terms of control, said Zhang Ya, a telecom expert with IDC in Beijing. She said authorities could develop filters, user identification methods and a management system to screen for undesirable messages. Currently, police screen cyber cafes and private Internet lines for pornography and anti-government Web sites. However, Ms Zhang said abusing SMS was not a common problem. 'It just happens occasionally,' she said.