Software manufacturers lost $29bn to piracy in 2003, more than double the previous year's losses, and about 36 per cent of software installations worldwide are pirated copies, an industry survey showed on Wednesday.

In dollar terms, the losses were greatest in western Europe, where piracy cut revenues by $9.6bn in 2003, followed by Asia and North America, the study by the Business Software Alliance (BSA) and International Data Corp (IDC) showed.

The BSA, a trade body, blamed the rapid spread of piracy on so-called peer-to-peer networks, in which internet users illegally swap software and other files such as music for free or at discounted prices.

"Peer-to-peer file-sharing services are becoming a huge problem for us," Jeffrey Hardee, BSA's Asia-Pacific director, said.

Highest piracy

Vietnam and China had the world's highest piracy rates, accounting for 92 per cent of all computer software installed in each country, followed by the Ukraine with 91 per cent, Indonesia at 88 per cent, and Zimbabwe and Russia with 87 per cent each.

Hardee identified Vietnam, China, India and Thailand as Asian countries that need to step up their fight against piracy.

"We need to see more [government] enforcement from these countries," he said.

The BSA represents leading computer software and hardware firms including Microsoft Corp, Apple Computer Inc, Hewlett-Packard Co Ltd, Intel Corp and International Business Machines Corp.