The bust yielded more than 300 copies of high-end counterfeit Microsoft software including XP Professional and Office Professional 2003 with a street value of $65,000, said Microsoft.

The raid was carried out by the Criminal Investigation Department's Intellectual Property Rights Branch, as well as representatives from Microsoft and its law firm Lee & Lee.

Microsoft's lawyers are currently reviewing the evidence collected, and are expected to apply to the Courts next week for a fiat. If successful, the move would give the tech giant permission to prosecute the alleged pirates.

Another 50 Microsoft 'certificate of authenticity' stickers, which are also believed to be fakes, were seized. These stickers are typically stuck onto new computers as proof that the machines are running original software.

Last November, The Straits Times reported that some dishonest computer system-builders were working with pirate syndicates to hoodwink consumers into buying high-end counterfeit software. The programs are so good that they are practically indistinguishable from the originals.

Microsoft's corporate attorney for intellectual property Jonathan Selvasegaram declined to name the shops raided as 'investigations are ongoing', but said they were 'fairly established' names at the mall. They have the same owner and are located on the 'higher floors' of the six-storey mall, he added.

Microsoft had received complaints from consumers who said their 'original' software had been flagged as pirated when they tried to use it.

Following a raid last July on a Chinese company that made counterfeit software, the authorities turned up evidence that the firm was shipping its products here.

This kicked off an 11-month investigation to identify the errant computer retailers that culminated in Thursday's raid, Mr Selvasegaram said. The sting also saw its investigators buying fake software from the shops to use as evidence.

The high-end counterfeits, he said, were a 'disturbing development' as they were very hard to distinguish from the originals. Microsoft has even created a website, www.howtotell.com, to help consumers identify and avoid high-end fakes.

Mr Selvasegaram said the company has several other leads it is looking at, but declined to elaborate.

However, Thursday's raid has created some ripples in the 'channel community' - computer retailers that buy software in bulk and then install it in the computers they sell to consumers. Mr Selvasegaram expects the remaining counterfeit software sellers to 'lie low' for now, although the company will 'continue to monitor the situation'.

Last November, the authorities raided six shops in Sim Lim Square that were selling devices to allow gamers to install and play pirated games on a handheld Nintendo device.

In the 1990s, Sim Lim Square was a place well-known for pirated materials, akin to Bangkok's infamous Pantip Plaza, but a series of crackdowns by the authorities saw the end of the Singapore shopping complex's blatant sale of pirated materials.

chuahh@sph.com.sg