The group posted a 24 per cent drop in annual profit and warned weak consumer demand and a lower pound could lead to an even bigger fall this financial year. Profit before tax and one-off items fell 24 per cent to £328m in the year ended February 28th.
It also said it would raise prices, cut costs and curb investment in a bid to cope with higher import costs.
But the firm, which sources around 80 per cent of products abroad, said it was not seeking to change analysts' consensus forecast for the current financial year, which suggests profits could fall by a further 40 per cent.
"Our main worry is the impact sterling may have on product pricing and therefore the impact it may have on consumer demand," chief executive Terry Duddy said.