Over one quarter of the population over 18 has neither a medical card nor health insurance, according to a new survey.

In addition, nearly two-thirds of immigrants have no public or private health cover, the survey found.

According to the survey by the Central Statistics Office (CSO) of those who had some form of medical cover, 24% indicated that they had a medical card only, 44% indicated that they had health insurance only and the remaining 5% had both a medical card and private health insurance.

Seventy-seven per cent of women had either a medical card or private health insurance, compared with 69% of men, while 28% of women had a medical card only, compared with 19% of men.

The CSO found that the proportion of adults without any medical cover decreases with age, with 4% of persons in the 18 to 24 age group having no medical cover, compared with just 1% among those aged 70 and over.

The survey was undertaken in the third quarter of last year. According to the CSO, the proportion of people with both a medical card and health insurance increased from 2% in 2001 to 5% in 2007.

Among those over 70, 10% had indicated in 2001 that they had both a medical card and health insurance, but this had risen to 33% by 2007.

The CSO said this level of medical card coverage for this age group increased from 79% in 2001 to 95% in 2007. This change was due to the introduction of medical cards for all over 70s regardless of income in 2001.

The report says there was a significant difference between the level of non-coverage for healthcare among non-Irish nationals compared to Irish nationals.

Sixty-one per cent of non-nationals had no healthcare cover (medical card or insurance), according to the survey.

The CSO said the level of non-coverage for healthcare among this group actually increased between 2001 and 2007.

This statistic, the CSO said, can be linked in part to the age profile of immigrants between 2001 and 2007, with the majority of immigration occurring in younger age groups where levels of medical cover are typically lower.