Tokyo: Japan is to launch a nationwide identification network on August 5 in a controversial scheme which has already been boycotted by communities fearful of a "Big Brother" society.

Each Japanese citizen will be given an 11-digit number in the basic resident registration network, commonly called Juki Net, enabling local governments to identify people online anywhere in the country.

The system will initially comprise a person's serial number, name, date of birth, sex, address and a record of any changes to these figures, although more information can be added under local ordinances in the future.

"Cows are given 10-digit numbers as a madcow measure, and human beings are put under surveillance with numbers with one extra digit," said a group of journalists, academics, lawyers and others who are opposed to the network.

The group warns of potential trouble if personal information in leaked. "There is no such thing as perfect security as the state claims," Citizen's League to oppose National ID Numbers said in a statement.

"Data will last forever and there are fears discrimination and prejudice could be systemised," it added.

The plan goes further than maintaining data efficiently, it creates a society under surveillance, the group said under a slogan, "No, to a stalking state."

Other opponents are apparently taking an even harder line. Prime Minister Junichiro Koizumi has received an anonymous threatening letter, which also contained what are believed to be shotgun pellets, demanding the government abandon the ID scheme.

Each resident can obtain a plastic card with an integrated circuitchip containing the six necessary items of information for some $ 10.

Japan's Trade Ministry plans to add more functions to the card in future so that it can be used as a health insurance pass, library card, a commuter ticket and even as membership to various shops, according to the group. It is the first consolidated database in which every citizen has a serial number under the same numbering system, as such data had previously been contained at local governments. Japan has separate numbering systems for health insurance, pension, and other public services.

While the Public Management Ministry says the scheme would boost administrative efficiency, opinion polls showed more than 80 per cent of people worry about information leaking out and violation of privacy.