By Clare Matheson BBC News Online business reporter

Some members have become "point jockeys", the group says

Nectar launched in a blaze of publicity last year, vowing to become the UK's biggest loyalty card programme for shoppers.

One year on, Nectar says it has just surpassed its promise to sign up 50% of the UK's households, with figures showing that there are about 13 million registered accounts.

However, only 10 million accounts have actually been used in the last 13 weeks.

Rob Gierkink, chief executive of Loyalty Management UK, which runs the Nectar scheme on behalf of its sponsors, is nevertheless upbeat.

"People who visit all four of our launch sponsors are twice as loyal - they become more engaged, in fact in some cases collectors do become 'points jockeys'."

Loyalty boon

Mr Gierkink adds that the scheme gets customers to spend more, promotes loyalty to its sponsors - including Sainsbury's, Debenhams, Barclaycard and BP - and brings in new customers.

A BP spokesman says the group's market share "surged" when it joined up.

HOW NECTAR POINTS ARE AWARDED Shoppers can redeem their points on various perks, such as cinema tickets or "free" money to spend on the sponsors' products. Sainsbury's: 2 points per �1 spent Barclaycard: 1 point per �2 spent on the credit card Debenhams: 2 points per �1 spent BP: 1 point per litre of fuel bought Thresher Gp: 2 points per �1 spent Adams: 2 points per �1 spent Ford: 2 points per �1 spent

Barclaycard's spokesman Ian Barber adds: "People don't purely get credit cards on the basis of loyalty schemes - but it certainly has brought in new customers."

He estimates up to two million customers have joined Barclaycard on the strength of the scheme, which sees any points earned on the credit card automatically transferred to the holder's Nectar account.

"Most important is it means people are using Barclaycard rather than the other two or three credit cards they have in their wallet."

Bitter sweet

But the scheme has had its problems.

For example, BP was unable to give out Nectar points at its 59 Safeway partnership stations as the firm was "not happy" about giving out points to a scheme it did not belong to.

However, that will be resolved by 22 September 22, BP says.

The scheme has also faced allegations of being a "big brother" figure, hoovering up and storing information on consumers.

Big Brother? Nectar knows what you buy at the shops

But, Mr Gierkink says that building up such information merely allows companies to make "better offers" targeted to their previous purchases.

"A family of five is very different to a single person household, it's not very useful to target the two with the same offer."

He stresses data is not sold and is only used for special offers between sponsors.

Not enough points?

More damaging was some scathing criticism from Which? magazine, which found that the Nectar scheme was among the worst on offer.

Which? said some consumers who spent �5,000 on Barclaycard received as little as �12.50 in points to redeem, while Sainsbury's customers had to spend as much as �1,000 just to get two tickets to the cinema.

As they build up big payouts people do base their shopping habits around loyalty schemes. Edward Ripley Datamonitor

But Mr Gierkink denies claims that Sainsbury's customers are having to spend more than they did with previous loyalty schemes to get their points.

"Customers at Sainsbury's are earning 70% more points than before. The only difference is that there are now many more places to collect points."

The scheme has already added more firms to the original gang of four - BP, Sainsbury, Barclaycard and Debenhams.

Now Vodafone, Ford, Threshers and Adams also allow shoppers to collect points as they spend.

Adams financial director Kavan Witts says: "Average transaction volumes have seen a definite benefit, as for new customers we're pretty certain our figures would indicate the scheme is working."

A free lunch

Do consumers, however, actually get something for nothing with the scheme?

Edward Ripley at Datamonitor says: "Analysis shows that on average credit card issuers with loyalty schemes charge slightly higher annual percentage rates.

"Loyalty schemes are increasingly expensive and the firms need to recoup their money."

But he adds that most people use the cards fairly responsibly.

"With the higher charge, they pay off their debt before incurring the monthly charge - and so may as well get the loyalty points.

It may not have a card, but low prices keep Asda customers loyal

"Those people are getting something for nothing. As they build up big payouts people do base their shopping habits around such schemes."

So are people redeeming their points to collect their rewards? Moneyexpert.com thinks not.

Only 56% of Nectar members said they collected rewards within a year, according to its findings.

Nectar member Amanda Jones, of Golborne, Cheshire, says she has not yet redeemed the 200 or so points she has racked up since joining the scheme at its launch last year.

And has it made her loyal to particular outlets? Well, not really, she didn't even know BP and Adams were now part of the scheme.

Loyalty to low prices

Meanwhile, analysts KPMG found only 2% of people said that loyalty cards meant they always stayed faithful to that brand and never shopped around.

In fact, most studies claim lower prices, rather than loyalty schemes, will keep customers coming back for more.

Recent supermarket figures may go some way to proving that point.

In July, it was announced Asda - famous for its low pricing - had overtaken Sainsbury's to become the UK's second biggest supermarket, with a 17% share of the market compared to Sainsbury's 16.2%.