Asked if the threat of AIDS had caused them to alter their sexual activities, 60.2 percent of women and 44 percent of men, said no, the survey published in weekly newspaper Expresso found.

One third of those surveyed, 33.5 percent, said they never use a condom during sexual relations while 28.8 percent said they only do so in certain cases, it found.

Of the 8.3 percent of respondents who said they frequently or occasionally used the services of prostitutes, 15 percent said they used condoms only sometimes and 6.7 percent said they never did.

Men were more likely to visit prostitutes than women, with 12.9 percent of males surveyed saying they occasionally paid for sex and 3.1 percent saying they frequently did so.

Nearly a 10th of those surveyed, 9.9 percent, said they were homosexual or bisexual.

Just over half, 50.8 percent, of those who said they were homosexual said they acknowledged it socially, compared to just 14.3 percent of those who said they were bisexual.

Pollster Eurosondagem interviewed 726 people, 369 women and 357 men, in person between December 13 and 20. The margin of error was 3.6 percent.

Portugal had an HIV incidence rate of 78.6 cases per one million people, compared to an average of 14.2 cases in the 25-member European Union, in 2003,

the last year for which comparative figures are available from Eurostat, the bloc's statistics office.

It was also the only nation among the older 15 EU nations where the incidence rate of HIV rose between 1994 and 2003, increasing from 68.1 to 78.6.