DHAKA, Mar 11 - Bangladesh has blocked 1.5 million mobile numbers and tightened regulations for buying and selling SIM cards following a spike in cellphone-related crime, an official said Thursday.

Under new rules, children under 18 will be barred from buying a SIM card and adults will have to show their national identity cards to register new mobile numbers, Home Secretary Abdus Sobhan Shikdar told AFP.

"Police have disconnected over 200,000 phones which were being used in cases of extortion and hasslement," he said, adding that a further 1.3 million numbers were blocked because they lacked full registration documents.

SIM cards, the unique data card for each phone, can currently be purchased without providing any identification which has led to a spike in abusive or criminal calls that are hard to trace, he said.

Under the new rules, which have been approved by the home ministry, licensed SIM card retailers must also obtain police clearance.

The move follows a string of reports in local media about death threats -- issued on hard-to-trace pay-as-you-go mobile phones -- to political leaders and high-profile businessmen.

Bangladesh's mobile phone subscriber base has grown from 1.5 million in early 2003 to around 54 million in January this year, thanks to a price war among operators and a booming economy growing at an average six percent a year.