Sainsbury's has announced it will cut the number of Nectar reward points on offer to members of its loyalty scheme.The supermarket giant said that from 11 April the number of points customers earn for every pound spent in store or online will drop from two to one, while customers will also no longer be awarded points for every bag they reuse."We are changing the way customers earn Nectar points and launching more high-value bonus events, like 'Swipe to Win', 10xpoints on fuel and adding more categories to our Christmas 'Double Up' event so that customers can make their points go even further," a Sainsbury's spokesperson said.The firm added that its Nectar card scheme remained good value for money and, in an email to customers, said there would be "lots of new opportunities to boost your balance faster and more value when you spend your points".Sainsbury shares closed down 1.11% to 226.17p on Tuesday.