It is hoped the new, more detailed questions, will help government departments and local authorities create a clearer picture of the UK's ethnic and religious make-up.

Anthony Lerman, director of the Institute of Jewish Policy Research, says a lot depends on how questions are asked

A White Paper on the 2001 Census is being published in the House of Commons at 1300GMT.

In previous censuses, people in England, Wales, Scotland and Northern Ireland were given the opportunity to categorise themselves as white, black or Asian.

'Who am I?'

But the 2001 Census will give respondents a much wider range of categories - such as African, Afro-Caribbean, Bangladeshi or White. For the first time those ticking the latter box will also be asked whether they are Irish.

They will also be able to denote their religious affiliation, including Anglican, Roman Catholic, Baptist, Jewish, Muslim, Hindu and Sikh.

The aim is to give government statisticians a clearer picture of who lives in the UK and will help to combat racism by promoting multi-ethnicity.

The 2001 Census is expected to lead to the first accurate assessment of the number of Muslims in the UK. Muslims, believed to be Britain's largest religious minority, are variously estimated at between one and three million.

In Census trials in 1997 respondents were asked if they had a religious faith and were offered the following responses: None, Christian, Hindu, Jewish, Muslim, Sikh, Buddhist or Other.

It is hoped the 2001 Census will give clearer data

Anthony Lerman, director of the Institute of Jewish Policy Research, said he had no problem with the new questions but he said a lot depended on how they were asked.

"In the last Census the question was asked about ethnicity for the first time but it was prioritised with White above other groups and it was essentially colour-coded."

In Scotland questions about ethnicity and religion will be omitted because of its low black and Asian population.

The form will also be worded in such a way that statisticians can work out how many gay people are living as couples.

Asking about earnings

But the Census is not expected to include questions about earnings, after they were poorly received in the Census trials.

Last week the Office for National Statistics (ONS) awarded a £50m contract for processing the 30 million Census forms to US computer company Lockheed Martin.

Around 50,000 "enumerators" - volunteers paid on a piecemeal basis - will still be used to hand out the forms.

But respondents will, for the first time, be given the option of posting their forms.

Forms from England and Wales - and possibly those from Scotland and Northern Ireland too - will be processed by a "data capture" computer in Runcorn, Cheshire.

'Priceless information'

An ONS spokesman admitted the information contained in the Census was highly coveted by marketing companies but he said: "Confidentiality is paramount.

"The Census forms are kept under lock and key for 100 years and no information is given to outside companies or even to other government departments."

He said the information supplied would be broken down into pure statistics, which would then be available to government departments, local councils, health and education authorities.

The vast majority of the form will be tickboxes, which can be easily read by computers.

He said computerisation would significantly speed up the process of obtaining useful data from the Census, which took up to three years after the 1991 Census.

Although everyone is legally obliged to fill in and return the forms, it is thought around 2% of the population - a million people - were missed by the last Census.