While figures show an increase in those speaking Welsh, data shows that the language is losing ground in its rural heartland, while gaining strength in urban areas.

Welsh historian, Dr John Davies, told BBC Wales: "Welsh is becoming not a rural language, but an urban language and it's gaining strength in places like Cardiff.

"In the 1950s only about 5% of Welsh speakers lived within 10 or 20 miles of Cardiff, now it's 10%."

A total of 96 per cent of the population of Wales gave their ethnic origin as White British.

In Wales, there were increases (compared with 1991) in the proportion of Indian, Pakistani, Bangladeshi and Chinese people, and 0.6 per cent classified themselves in 2001 as mixed ethnicity.

In terms of health, the census found that rates of poor health were higher than the average for Engalnd and Wales.

The south Wales Valleys county of Merthyr Tydfil has the highest (18.1%) followed by Blaenau Gwent, Neath Port Talbot, Rhondda Cynon Taff, Caerphilly, Carmarthenshire and Torfaen.

The census was held during the foot-and-mouth crisis of 2001, but organisers said neither that, nor protests over the absence of a tick-box for people to register that they were Welsh, affected the numbers who supplied information.

In all, 41 questions on areas ranging from housing to ethnic background were asked.

The results of the census will be used to determine how public money should be spent and the needs of the population in different areas of Wales.

The population figures already released showed that Wales is more populous and marginally more elderly than a decade ago.

And they revealed that some areas of Wales were growing rapidly, while the population of some rural and valleys areas was shrinking.

The population of Ceredigion grew by 19.5%, Cardiff's by 7% and Denbighshire's by 7%.

Merthyr Tydfil lost 5.6% of its population in 10 years with Blaenau Gwent, Anglesey and Neath Port Talbot also recording fewer inhabitants than a decade previously.

The census also showed that Cardiff is becoming a younger city with 24.1% of its population aged between 20 and 34, compared to 18% in Wales as a whole.