A controversial and long-delayed identity card scheme is finally been introduced in Nigeria.

Some 60,000 centres were due to open nationwide on Tuesday for a period of two weeks for an estimated 60 million adults to register in Africa's most populous nation.

The importance of the programme cannot be over-emphasised President Olusegun Obasanjo

However, some northern politicians oppose the scheme, fearing it will be used to cross-check other population records, including the voters roll.

Correspondents say that population figures are often inflated in order to increase access to government resources.

Some southerners say that the population in the north is far lower than official figures suggest.

Such argument have delayed a census, which was supposed to have been conducted in 2001, 10 years after the last one in 1991.

'Foolproof'

The BBC's Mannir Dan-Ali in Abuja says that he only saw one registration centre open and it was extremely disorderly.

Deputy Interior Minister Odion Ugbesia said that "foolproof" measures have been taken to prevent fraud, double registration and foreigners from getting Nigerian identity cards.

The authorities say the card will defeat fraud

The cards will include fingerprints and photographs, as well as the name, address, occupation, state of origin and height of the bearer.

The idea of a national identity card was first mooted in 1978 by current President Olusegun Obasanjo, who was then Nigeria's military ruler.

Several contracts to produce identity card have been cancelled following changes of power, amid allegations of fraud.

Mr Obasanjo says that the scheme will help government planning and to fight fraud and corruption.

"The importance of the programme cannot be over-emphasised in the country," he said in a recent interview.

It will not be obligatory to have an identity card but correspondents say that it might be necessary to obtain government services.

Officials deny that it is linked to the forthcoming election in April.