Police say Chen Ing-hau, 24, has not been charged and their investigation is in its early stages.

He is said to have offered his help in efforts to counteract the virus.

Francis Markus in Taipei: Mr Chen "didn't intend to cause such massive damage"

Hundreds of thousands of computers in Asia and the Middle East had their data wiped by the malicious programme on 26 April - the anniversary of the Ukrainian nuclear disaster in 1986.

Police say Mr Chen - who recently graduated from Taipei's Tatung Institute of Technology but is currently doing his military service - has said he did not intend to cause such massive damage.

Authorities say they are trying to clarify what, if any, legal responsibility he could face if convicted.

In Taiwan, intentionally spreading a computer virus is an offence that carries a possible three-year prison term.

Boasting to colleagues

Although popularly dubbed Chernobyl, the virus is known to experts as CIH.

According to Taiwanese media reports, Mr Chen's colleagues say he had acknowledged using his own initials in naming the virus.

Former classmates and instructors said he had boasted of creating the Chernobyl virus and warned friends not to download it into their computers.

Some reports said Mr Chen had been reprimanded quietly by his institute a year ago but not further disciplined, prompting an Internet debate about Taiwan's vigilance against cybercrime.

Deadly effects

The United States and Europe largely escaped the virus's effects this week, as companies had protected their computers with anti-virus programs that killed it.

But in Asia and the Middle East the same precautions had in many cases been ignored.

Chernobyl also spreads through pirated software, which is rife in these parts of the world.

Chernobyl is less widespread than the e-mail replicator virus Melissa, but it has been warned to be far more serious, especially on Windows 95 or 98 machines.