Online and mail order retailer N Brown upped its interim dividend by over 50% as strong sales over the internet and a better bad debt picture lifted underlying profits by 13%.E-commerce sales in the half year to August jumped by 21% to £128m out of a total of £339m, up from £323m, with underlying profits up to £41.8m. Pre-tax profits fell to £33.3m from £38.5m after an £8.5m charge for mark downs of financial instruments.The sales increase came despite tighter credit controls for customers Brown considered a risk as the recession spread. Active established customers on average spent 2% more than in the corresponding period last year. Revenue in the first 6 weeks of the second half is 1% ahead of last year, although this period compares with a particularly buoyant trading period and the weeks ahead provide less challenging comparatives, the statement said.Second half online sales are up 15% so far and Brown is boosting its customer recruitment expenditure, "while at the same time there are a number of signs emerging that the trends which influence bad debts are starting to settle down," it added. "As a result the board remains confident that we are on track to deliver on our expectations for the 2009/10 financial year."The interim dividend rises by 1.6p to 4.38p, up 58%, though Brown says this in part reflects a rebalancing between half and full year payments.