Amid a police warning that stern action will be taken against anthrax pranksters who are causing "unnecessary panic" in the country, de facto Law Minister Dr Rais Yatim said today that it will be difficult to track down the culprits.

Over the past few days several embassies, companies and even the Bukit Aman federal police headquarters have received suspicious powdery substance in envelopes.

This prompted the inspector-general of police Norian Mai to warn pranksters yesterday that their irresponsible actions have been classified as "attempted murder".

Norian also did not rule out the possibility of using the Internal Security Act - which provides for detention without trial - against those responsible.

But Rais said today the nature of the crime makes it difficult to trace the culprits."Who are you going to prosecute?" he asked.

Rais was speaking at a press conference after opening the 2001 Emergency Response Planning Conference at the Senior Police Officers' Training College in Kuala Lumpur.

Elaborating on the legality involved, the minister said after identifying the content of the substance, the authority has to evaluate the hazards caused by the powdery substance.

He added it is important to determine if the substance was indeed anthrax and evidence wise, the properties of anthrax must also be specifically established by the Chemistry Department.

"Once we get the report from the chemistry department, that says 'this is anthrax', then the question would be whether it is a crime to send such substance in the envelope or in the container," he said.

Anthrax scare

The first anthrax scare in Malaysia surfaced last week when a 'suspicious letter' was sent to a factory in Penang from the United States. Following this, several other cases were also reported.

Yesterday, the US embassy, the Australian high commission, Bukit Aman and the Malaysia Airlines office in Kuching, Sarawak, were reported to have received letters with suspicious substance.

However, authorities are yet to verify whether the letters contained anthrax spores.

According to a report in China Press today, initial results in a study carried out by the Veterinary Research Institute showed that the letters suspected of containing anthrax reported in Penang were negative.

Anthrax is an acute infectious disease caused by the spore-forming bacterium bacillus anthracis. It is commonly found in animals such as cattle, sheep and goats. It is most common in agricultural regions and is not easily spread between humans.

Since the US and its allies launched their military strikes against Afghanistan, there has been widespread fear of bio-terrorism. Three Americans have died from exposure to the bacteria while scores are being treated.